Tuesday, June 11, 2013
Derby Server and Administration Guide
Derby Server and Administration Guide
http://dba.fyicenter.com/guide/Derby-Server-and-Administration-Guide/
This guide explains how to use Derby in a multiple-client environment. It also provides information that a server administrator might need to keep Derby running with a high level of performance and reliability in a server framework or in a multiple-client application server environment.
Please visit this site:
http://dba.fyicenter.com/guide/Derby-Server-and-Administration-Guide/
Thank you,
Team DBAFYI - DBA Resource Center
http://dba.fyicenter.com/
Wednesday, October 05, 2011
The Information Security Glossary About Database
*** The Information Security Glossary About Database ***
Database Administrator - DBA
A 'DBA' is a highly technical person who has specialised in the development and maintenance of databases and database applications. The DBA is responsible for ensuring that all housekeeping routines are performed on the database, which may include designing and maintaining the structure and content of the (many) tables which together form the database, and the relationships between these tables. In addition, the DBA will usually be specialised in writing reports and querying the database, usually using Structured Query Language - or SQL.
Datascope
An electronic device that is capable of detecting and reading the bit-patterns of data passing down a communications line and interpreting/translating these patterns into readable alphanumeric characters.
Some devices are capable of detecting/reading the electromagnetic radiation emitted directly by computers without the need to 'tap' a communications line.
Dead Tree Edition
Techie slang for 'Hard Copy' - i.e. anything printed on paper, rather than held on computer media.
An ironic reference to the source of the paper required.
Debug
To trace and fix faults (bugs) in computer software and, occasionally, hardware. The term derives from the same source as Bug.
Deciplegic
Mouse Potato suffering from Trigger Finger.
Decryption
The process by which encrypted data is restored to its original form in order to be understood/usable by another computer or person.
DED
Dark-Emitting Diode (non-functioning Light Emitting Diode), a Friode.
Default
A default is the setting, or value, that a computer program (or system) is given as a standard setting. It is likely to be the setting that 'most people' would choose. For example, the default font on your word processor maybe Times New Roman 10 pitch; unless you change this, it will remain at the default setting.
Defaults are used throughout the computer industry to enable software to work 'out of the box' and not require ordinary people ('Users') to spend hours selecting every conceivable option in advance - quite thoughtful really!
Default Password
The password installed by a manufacturer and required to access a computer system when it is initially delivered, or a password required by software (typically shareware) to prove that the user is registered with the software vendor. Default passwords are not normally encountered on new PCs and have become relatively rare, but, in cases where such a password has been installed, the new owner of the equipment should change it at the earliest opportunity, to avoid it being known to third parties.
There are a range of default passwords known to everyone; and these are the first ones tried by anyone hacking into, or merely attempting opportunistic access. Such passwords as 'password', '123456' and ' ' i.e. blank (nothing) must be changed immediately. If you have one of these or similar passwords; please change it now. RUSecure™ will still be here when you have finished!
Denial of Service
A Denial of Service (DoS)attack, is an Internet attack against a Web site whereby a client is denied the level of service expected. In a mild case, the impact can be unexpectedly poor performance. In the worst case, the server can become so overloaded as to cause a crash of the system.
DoS attacks do not usually have theft or corruption of data as their primary motive and will often be executed by persons who have a grudge against the organisation concerned. The following are the main types of DoS attack :-
* Buffer Overflow Attacks; whereby data is sent to the server at a rate and volume that exceeds the capacity of the system; causing errors.
* SYN Attack. This takes places when connection requests to the server are not properly responded to, causing a delay in connection. Although these failed connection will eventually time out, should they occur in volume, they can deny access to other legitimate requests for access.
* Teardrop Attack. The exploitation of a features of the TCP/IP protocol whereby large packets of data are split into 'bite sized chunks' with each fragment being identified to the next by an 'offset' marker. Later the fragments are supposed to be re-assembled by the receiving system. In the teardrop attack, the attacker enters a confusing offset value in the second (or later) fragment which can crash the recipient's system.
* Smurf Attack or Ping Attack. This is where an illegitimate 'attention request' or Ping is sent to a system, with the return address being that of the target host (to be attacked). The intermediate system responds to the Ping request but responds to the unsuspecting victim system. If the receipt of such responses becomes excessive, the target system will be unable to distinguish between legitimate and illegitimate traffic.
* Viruses. Viruses are not usually targeted but where the host server becomes infected, it can cause a Denial of Service; or worse.
* Physical Attacks. A physical attack may be little more that cutting the power supply, or perhaps the removal of a network cable.
DES / AES
DES - The Data Encryption Standard and the AES - Advanced Encryption Standard are both data encryption standards for the scrambling of data to protect its confidentiality.
It was developed by IBM in co-operation with the American National Security Agency and published in 1974. It has become extremely popular and, because it used to be so difficult to break, with 72,000,000,000,000,000 possible key variations, was banned from export from the USA. However, restrictions by the US Government, on the export of encryption technology was lifted in 2000 to the countries of the EU and a number of other countries.
The AES - Advanced Encryption Standard, is a state of the art algorithm (developed by Rijndael) and chosen by the United States National Institute of Standards and Technology on October 2, 2000. Although selected, it will not become officially "approved" by the US Secretary of Commerce until Q2 2001. Meanwhile, products are already available which use the Rijndael algorithm within AES encryption tools. For example http://www.privatecrypt.com/int/.
Desktop
1. Verbal shorthand for Desktop Personal Computer, normally used to differentiate such a system from a 'Laptop' or portable PC.
2. In Windows 95®, and later releases, the screen visible on the computer monitor is known as the desktop and can be used to store programs and data as if it were a normal directory/folder. It is generally considered better practice to use the desktop as a place to store links to files and programs, rather than the files and programs themselves. This is partly because of the risk of accidental deletion, but - more importantly to companies - to avoid such files being visible to any curious passer-by.
Development Library
An area of the computer systems' fixed storage area which is set aside for the development of software, to minimise/avoid the possibility of conflict between an existing program and a new version.
Development Machine
An additional computer system, not part of the main processing system. Usually smaller than the main system, but similarly configured, the development machine is used for creating new software, amending existing software, and testing such creations and amendments to ensure that there is no possibility of the daily work and security of the main system being compromised by conflict between different versions of the same program. The development machine may also be used as a contingency standby machine, in case of failure of the main system. Companies unable to justify the costs of duplicate machines should use a Development Library within a partitioned area of the main system.
DHTML
Dynamic HyperText Markup Language. Contrary to its name, DHTML is not a new version of HTML - the Hyper Text Markup Language used to generate Web pages. DHTML is the combination of several browser features which, together, permit a Web page to be more 'dynamic'. Dynamic in this sense means the ability for the Web page to change its look and features after the page has been loaded; perhaps dependent upon the selection of various options. The recent versions of the most popular Web browsers all offer DHTML support.
Digital
Employing the binary system of numbers (1 and 0 only) for processing purposes.
Digital Certificate
A digital certificate is the electronic version of an ID card that establishes your credentials and authenticates your connection when performing e-Commerce transactions over the Internet, using the World Wide Web.
To obtain Digital Certificate an organisation must apply to a Certification Authority which is responsible for validating and ensuring the authenticity of requesting organisation. The Certificate will identify the name of the organisation, a serial number, the validity date ("from / to") and the organisation's Public Key where encryption to / from that organisation is required.
In addition, the Digital Certificate will also contain the Digital Signature of the Certification Authority to allow any recipient to confirm the authenticity of the Digital Certificate.
A global standard (X. 509 Public Key Infrastructure for the Internet) defines the requirements for Digital Certificates and the major Certificate Authorities conform to this. Such standards, and the integrity of the Certificate Authorities are vital for the establishment of 'digital trust', without which e-Commerce will never attain its potential.
Digital Signature
A digital signature is an electronic equivalent of an individual's signature. It authenticates the message to which it is attached and validates the authenticity of the sender. In addition, it also provides confirmation that the contents of the message to which it is attached, have not been tampered with, en route from the sender to the receiver.
A further feature is that an e-mail 'signed' with a digital signature cannot easily be repudiated; i.e. the sender is not able to deny the sending and the contents of the message; plus it provides a digital time stamp to confirm the time and date of transmission.
For a digital signature to be recognised, and acknowledged as something of integrity, it needs to be trusted by the recipient. It is for this reason that a Certification Authority will supply a digital signature to persons, the identity of whom, it has been able to verify; perhaps by having an Attorney's stamp on a document which validates the applicant's name, address, date of birth etc.
To provide greater digital trust, the Digital Signature is packaged with the certificate of the Certification Authority, and this too may be inspected for validity and expiration.
Most people expect digital signatures to totally replace the use of the ('old fashioned') pen and ink signature with orders and authorities being accepted via digitally signed e-mails, the contents of which may, or may not, be encrypted for additional security.
N.B. In July 2000, Digital Signatures became legally accepted in the United Kingdom under Section 7 of the Electronic Communications Act. In the USA also, Congress approved the use of Digital Signatures for certain types of e-Business around the same time under the E-Sign Act. Because both Acts are extremely new, it is strongly recommended that legal advice be sought before reliance is placed upon this new legislation.
Digital Versatile Disk - DVD
Currently, these optical storage disks are being pioneered by the entertainment business; notably because the DVD is able to store a full length feature movie on a single CD size disk, with faithful reproduction of visual and audio quality.
DVD, with a capacity (using both sides of the disk) of approx. 17GB, will doubtless replace the present CDs / CD-ROMs with their 'modest' 670MB capacity. At present consumer models are read only, but they will soon offer full record capability with integration into information systems.
Digital Watermark
A unique identifier that becomes part of a digital document and cannot be removed. The watermark is invisible to the human eye but a computer can analyse the document and extract the hidden data. Digital watermarks are being used for Classified/Top Secret documents - usually Military/Governmental - and highly confidential commercial material. The primary use of such marks is to allow different marks to be used when the document is copied to different persons and thereby establish an Audit Trail should there be any leakage of information.
Disable
The process by which hardware or software is deliberately prevented from functioning in some way. For hardware, it may be as simple as switching off a piece of equipment, or disconnecting a cable. It is more commonly associated with software, particularly shareware or promotional software, which has been supplied to a user at little or no cost, to try before paying the full purchase or registration fee. Such software may be described as 'crippled' in that certain functions, such as saving or printing files are not permitted. Some in-house development staff may well disable parts of a new program, so that the user can try out the parts which have been developed, while work continues on the disabled functions.
Disabling is also often used as a security measure, for example the risk of virus infection through the use of infected floppy diskettes can be greatly reduced, by disconnecting a cable within the PC, thereby disabling the floppy drive. Even greater protection is achieved by removing the drive altogether, thereby creating a diskless PC.
Disaster Recovery Plan - DRP
The master plan needed by technical and non-technical staff to cope with a major problem - such as the Boeing Syndrome. Do not confuse and merge the DRP with the Business Continuity Plan. The DRP is the plan which is activated when there is an emergency. It is the plan which ensures that health and safety come first followed by damage limitation. Having contained the impact of the disaster, and having ensured that the situation is now under control e.g. through the Emergency Services, then the Business Continuity Plan will be activated.
One of the most difficult aspects of a DRP is agreeing when it should be activated. In some circumstances it will be clear. For example, a tornado destroys part of the office block; or a serious fire reduces the premises to ashes. However, on many occasions, disasters have multiple warnings or indicators, and it is these which need to be considered and identified as the triggers to invoke your DRP.
N.B. The skills required to prepare and manage a DRP are not necessarily the same as those required for a Business Continuity Plan.
Distributed Processing
Spreading the organisation's computer processing load between two or more computers, often in geographically separate locations. If a organisation has the necessary financial and technical resources, distributed processing, with mirroring between sites, is an excellent contingency plan for sudden disasters.
Even if there is a total loss of one system, the remaining computer(s) can carry the load without disruption to users and without loss or corruption of data.
DMZ
A DMZ - De-Militarised Zone, is a separate part of an organisation's network which is shielded and 'cut off ' from the main corporate network and its systems. The DMZ contains technical equipment to prevent access from external parties (say on the Internet) from gaining access to your main systems.
The term comes from the buffer zone that was set up between North Korea and South Korea following their war in the early 1950s. A DMZ is not a single security component; it signifies a capability. Within the DMZ will be found firewalls, choke and access routers, front-end and back-end servers. Essentially, the DMZ provides multi-layer filtering and screening to completely block off access to the corporate network and data. And, even where a legitimate and authorised external query requests corporate data, no direct connection will be permitted from the external client, only a back-end server will issue the request (which may require additional authentication) from the internal corporate network.
However, the extent to which you permit corporate data to be accessible from and by external sources will depend upon the value of the Business Assets which could be placed at (additional) risk by allowing access to (even) pre-specified data types.
DNS
Domain Name System (or Server). The DNS is the means by which user friendly Web addresses are translated into arcane IP addresses. The DNS ensures that your are routed to the correct site.
Domain Name
The domain name identifies the location of an organisation or entity on the Internet and, through Domain Name Service translates this to an IP Address, which is the real address to which traffic destined for that domain name is routed.
Dongle
A mechanical device used by software developers to prevent unlicenced use of their product. Typically, a Dongle is a small connector plug, supplied with the original software package, which fits into a socket on a PC - usually a parallel port, also known generally as the LPT1 Printer port. Without the Dongle present, the software will not run. Some older Dongles act as a terminator, effectively blocking the port for any other use, but later versions have a pass-through function, allowing a printer to be connected at the same time. Even though the PC can still communicate with the printer, there have been problems with more recent printers which use active two-way communications with the PC to notify printing status, ink levels, etc.
Down
In IT terms, when a system is down, it is not available to users. This is not necessarily due to hardware or software faults, it may well be necessary to disconnect non-IT users, or take the system down for maintenance, installation of new hardware, loading new software etc. Traditionally such activities would take place after the End of Day, but the advent of 24x7 processing means there is no natural break in the cycle, and IT staff will therefore schedule the work for the time of minimum system workload - probably around 03:00 on Sunday morning!
Downtime
The amount of time a system is down in a given period. This will include crashes and system problems as well as scheduled maintenance work. Obviously, downtime impacts upon system availability, and most IT departments will maintain a downtime log to record when, and why, the system was not available to users. This log should be reviewed at intervals to identify any recurring problems, failure patterns etc.
DPI
Dots Per Inch. A measure of resolution for equipment such as printers and scanners. The more the better.
Drill Down
Descending through numerous layers of consolidations, summaries, etc., etc., to reach the really detailed information at the bottom.
Driver
A driver is a small interface program which allows a computer to communicate with a peripheral device, such as a printer or a scanner. The driver will be automatically installed when you connect the device to the PC; hence the need for a CD-ROM or floppy disk when installing such peripherals.
Dual Control
A control procedure whereby the active involvement of two people is required to complete a specified process. Such control may be physical; e.g. two persons required to unlock the Data Safe, or logical; as in the case of a higher level authorisation password required to permit the entry of data created or amended by another person.
Dual Control is one of the foundations of Information Security as it is based upon the premise that, for a breach to be committed, then both parties would need to be in collusion and, because one should always alternate the pairs of people, it would require a much greater level of corruption in order to breach dual control procedures; especially is such procedures require nested dual control access, such that (say) 2 pairs of people are required to enable access.
If this procedure appears someone 'dated' in today's 21st century 'wired' environment, please note that in 2000 a number of vendors started to sell 'Trusted Operations Systems', which enforce the requirement for dual control and the separation of duties, to provide substantially greater Information Security.
Dumb Terminal
A type of terminal that consists of a keyboard and a display screen that can be used to enter and transmit data to, or display data from, a computer to which it is connected. A dumb terminal, in contrast to an intelligent terminal, or PC, has no independent processing or storage capability and thus cannot function as a stand-alone device.
e-
Widely used - now widely overused - abbreviated prefix indicating 'electronic'.
Given the current frenzy for on-line services, companies are sticking the 'e-' prefix onto the front of almost any word to show how progressive and technologically advanced they are :-
e-business, e-commerce, e-trading, e-finance, e-broking, e-shopping, e-retailing, e-money, e-cash, e-purse, e-wallet, - the list is (probably) endless.
Earwigging
Alternative (slang) term for Eavesdropping.
Eavesdropping
Listening to someone else's conversation. In its most basic form, it amounts to one person keeping within earshot of a conversation between two other persons, but in the security and IT worlds it extends to remote listening and recording devices, include the interception of telephone calls, fax transmissions, e-mails, data transmissions, data-scoping, and even radio scanning for mobile communications.
The security implications for companies are primarily that user identification details or passwords can become known to criminally inclined individuals, or that confidential/sensitive information about the organisation, its finances, or activity plans may leak to competitors.
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e-Commerce
e-Commerce, e-Business or e-Tailing is an electronic transaction, performed over the Internet - and usually via the World Wide Web - in which the parties to the transaction agree, confirm and initiate both payment and goods transfer; at the click of the mouse.
There are two general types of e-Commerce activity; Business to Consumer (or Business to Customer) - B2C, and Business to Business - B2B.
Business to Consumer is usually, but not always, characterised by the purchase of goods or services, using the "shopping cart" metaphor and the acceptance of credit / debit cards in payment.
Business to Business, on the other hand, is concerned with using the Internet to place and receive orders from other businesses; establishing legally binding contractual commitments and pooling the resources of companies across the globe to tender for a project, with each party being authenticated and legally bound by their digital commitments.
However, to achieve this, and for e-Commerce to reach its true potential requires 'digital trust', and for this to take place requires strong technical tools to authenticate, encrypt and assure the confidentiality of data. Whilst e-Commerce can be initiated using e-mail, this requires the adoption of Digital Signatures which not only authenticates the sender, it also confirms the time and date of transmission and assures that the contents of the transmission were not tampered with.
Transactions initiated using Web servers, usually rely upon Digital Certificates and the use of the Secure Sockets Layer authentication and encrypted communication standard. In addition, to provide security for the secure transmission of documents, and other data, the use of the RSA standard is common, with Public Key Infrastructure (PKI) being used to create, issue and manage the use of public and private keys (or Digital Certificates).
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Editor
A program which allows a user to create, view, and amend, the contents of certain types of files. There are several types of editors, the most common being Text Editors, and Hex (Hexadecimal) Editors.
Editors work at the lowest level, either in ASCII (Text Editor) or directly with disk contents (Hex Editor).
Although text Editors, e.g. Notepad in Windows®, are common, companies should give consideration to staff access to Editors, particularly the more powerful types - such as Hex Editors. A Hex Editor can do considerable damage to the contents of computer files, which may not be recoverable.
NB, Although Word Processors and other programs can be used to edit their own files, they are NOT Editors in this context.
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Electronic Eavesdropping
Electronic eavesdropping is the intentional surveillance of data - voice, data, fax, e-mail, mobile telephones etc, often for nefarious purposes.
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End User
Usually reduced simply to User. The person who actually uses the hardware or software that has been developed for a specific task
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End User License Agreement - EULA
The End User License Agreement - or EULA - is a legally binding contract between the developer or publisher of a software program (or application) and the purchaser of that software. However, unlike the purchase of goods or services, the EULA is, as its name implies, a license agreement. In other words, the purchaser does not own the software, they merely have a right to use it in accordance with the licence agreement.
During the install of package software, the purchaser is shown the contents of the EULA and is often required to scroll down through the EULA, at the bottom of which, one may Accept or Refuse the terms of the EULA. By enforcing the need to scroll through the EULA, a user would be unlikely to succeed in any action to deny acceptance of the terms of the EULA.
In some cases, the EULA is written on the outside of the packaging with the breaking of the seal to the CD, indicating acceptance of the EULA.
In all cases, the EULA is the contract which users ignore at their peril; and whilst most EULAs contains broadly similar clauses and restrictions, it is important to confirm these before committing your organisation.
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Enforced Path
Normally, a user with the appropriate access control, is able to use any PC or workstation on the local area network to run an application or access certain data. However, where such data or system is classified as sensitive or requires restricted physical access, an enforced path may be applied. This is a straightforward configuration setting, performed by the Systems Administrator, whereby access is restricted to a specific workstation or range of workstations.
Enforcing the path will provide added security because it reduces the risk of unauthorised access; especially where such a workstation is itself within a secure zone, requiring physical access codes / keys etc.
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Enhancement
In theory, an improvement in hardware or software over the current version. In practice, enhancements are often merely vehicles to introduce some 'new' features into a package before withdrawing support for the current product, thereby pushing users towards upgrading their systems - at a price.
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Error Log
An error log records any abnormal activity on application software, usually in simple / plain text (ASCII). Each (main) application generates its own logs, and it is the responsibility of Systems Operations to retrieve and scrutinise them for any processing errors.
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Escrow
A legal provision whereby, in the event of a developer/supplier failing or otherwise ceasing to trade, the source code for their packaged software is made available to licensed / registered users, thereby enabling its ongoing maintenance.
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Extranet
An Extranet is a private network which uses the Internet protocols and extends beyond an organisation's premises, typically to allow access by clients, suppliers, or selected third parties.
Extranets require strong security if they are to prevent unauthorised access. This can range from a relatively simple User ID and password to the use of Digital Certificates, User IDs and passwords, with, naturally, end to end encryption of data.
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Fallback procedures
Fallback procedures are particular business procedures and measures, undertaken when events have triggered the execution of either a Business Continuity Plan or a Contingency Plan.
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Features / Glitches (Bugs)
Within the IT community, the term 'bug' is frowned upon, and is often replaced with the quaint term 'feature' or, a 'glitch'. Irrespective of how it is described, it remains a Bug !
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Fire Fighters
Net users who attempt to put out, or at least damp down, Flames/Flame Wars before they get out of hand. Rarely successful.
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Fire-Resistant Storage Cabinet
The legal records and documents of most organisations are likely to be in traditional paper / printer form. A fire resistant cabinet or safe is required tTo secure these documents from fire for a guaranteed period of time.
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Firewalls
Firewalls are security devices used to restrict access in communication networks. They prevent computer access between networks (say from the Internet to your corporate network), and only allow access to services which are expressly registered. They also keep logs of all activity, which may be used in investigations.
With the rapid growth in electronic communications - particularly via the Internet - firewalls, and firewall software, are being installed which will allow remote users to access limited parts of the system but restrict further access without satisfying specific identification and authorisation requirements. For example; an organisations' Web site will contain pages which are available to any Internet 'surfer' but other areas will not be accessible without recognition of authorised user status by the system. See Extranet.
Firewall Machine. A dedicated gateway computer with special security precautions on it, used to service outside network, especially Internet, connections and dial-in lines. The idea is to protect a cluster of more loosely administered machines hidden behind it from intrusion. The typical firewall is an inexpensive microprocessor-based Unix machine with no critical data, with modems and public network ports on it, but just one carefully watched connection back to the rest of the cluster. The special precautions may include threat monitoring, call-back, and even a complete iron box which can be keyed to particular incoming IDs or activity patterns.
Firewall Code. The code put in a system (say, a telephone switch) to make sure that the users can't do any damage. Since users always want to be able to do everything but never want to suffer for any mistakes, the construction of a firewall is a question not only of defensive coding but also of interface presentation, so that users don't even get curious about those corners of a system where they can burn themselves.
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Fit for Purpose
Fit for Purpose is a general expression which can be useful to ensure that Information Security solutions are appropriate for your organisation. Vendors will sometimes attempt to 'fit' their solution to your problem. Fit for Purpose is an expression which, when used within the solution negotiation context, places an onus of responsibility upon the vendor to ensure that its solution is (indeed) fit for the purpose which their client expects.
Example : a well known systems company contracted for the sale of their system. Inclusive in the price was one of week training in the system. During implementation it became apparent that one week for training was totally inadequate. The customer successfully claimed (prior to legal action) that the supplier's solution was inadequate and hence not fit for purpose.
When considering Information Security solutions, it is good practice to remind any potential suppliers in your requirement that the solution must be fit for purpose. See also Request For Proposal.
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Fix
An operational expedient that may be necessary if there is an urgent need to amend or repair data, or solve a software bug problem.
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Fixed Storage
The internal media used by a computer to store files, data, programs etc, and usually referred to as the Fixed Disk(s) or Hard Drive(s). Fixed storage devices obviously can be removed from the system for repair, maintenance, upgrade etc., but generally this cannot be done without a toolkit to open up the system for physical access by an engineer. The term is used mainly to differentiate these items from removable storage media such as tapes, floppy diskettes, CDs, etc.
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Flag
A message indication, sometimes, but not always, a warning to a user, which appears when a certain event takes place. For example, an inventory monitoring program may well 'flag' certain products when stocks fall below a predetermined level, to alert the user to re-order.
An alternative use is to warn of an event which will take place in the future, but has not yet occurred, for example, a financial institution aware of large cheque-based transaction on a customer's account may 'flag' the account to avoid an unauthorised overdraft.
Flags may be generated manually or automatically, depending on circumstances. In the case of the stock monitoring this would be automatic, while the cheque transaction example would be processed manually.
Automatic flags serve a useful purpose in drawing users' attention to situations which otherwise may be overlooked.
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Flame
'Flame' is abusive communication by E-mail or posting to a newsgroup, which attacks an individual or organisation for some real or imagined grievance. The real problem is broader than that of a few rude e-mails: flame represents the anarchistic side of the Internet. The flame may start with only one abusive message, but it is broadcast so widely that large numbers of unconnected browsers join in - often on both sides of the argument. This can lead to 'Flame Wars', where the traffic load becomes so high that communications network performance degrades, and E-mail boxes become blocked - as is the case with bottlenecking and mail bombing.
Problems for companies may arise if a member of staff has used an organisation's e-mail address to start the flame - another reason to monitor staff activities.
Flame has some redeeming features. Deeply unpleasant (or disturbed) individuals who posted lengthy racist (or sexist, or some other -ist) diatribes have found themselves flamed off the Net....
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Flame Bait
A Usenet posting or other message intended to trigger a flame war, or one that invites flames in reply. Acceptable for Usenet posters on a domestic machine, but not recommended in the office!
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Flash
Two meanings. Firstly, Similar to a Flag but more obvious and usually more urgent, or more serious, a Flash is a visual warning to a user, often associated with security control procedures. For example, if a user who is already logged on at one computer attempts to also log on at a second terminal, the system will Flash the IT supervisor console to warn of possible attempted breach of security.
Secondly; Flash is a technology being used to provide complex animation and sound on Web sites. It is extremely popular!
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Database Administrator - DBA
A 'DBA' is a highly technical person who has specialised in the development and maintenance of databases and database applications. The DBA is responsible for ensuring that all housekeeping routines are performed on the database, which may include designing and maintaining the structure and content of the (many) tables which together form the database, and the relationships between these tables. In addition, the DBA will usually be specialised in writing reports and querying the database, usually using Structured Query Language - or SQL.
Datascope
An electronic device that is capable of detecting and reading the bit-patterns of data passing down a communications line and interpreting/translating these patterns into readable alphanumeric characters.
Some devices are capable of detecting/reading the electromagnetic radiation emitted directly by computers without the need to 'tap' a communications line.
Dead Tree Edition
Techie slang for 'Hard Copy' - i.e. anything printed on paper, rather than held on computer media.
An ironic reference to the source of the paper required.
Debug
To trace and fix faults (bugs) in computer software and, occasionally, hardware. The term derives from the same source as Bug.
Deciplegic
Mouse Potato suffering from Trigger Finger.
Decryption
The process by which encrypted data is restored to its original form in order to be understood/usable by another computer or person.
DED
Dark-Emitting Diode (non-functioning Light Emitting Diode), a Friode.
Default
A default is the setting, or value, that a computer program (or system) is given as a standard setting. It is likely to be the setting that 'most people' would choose. For example, the default font on your word processor maybe Times New Roman 10 pitch; unless you change this, it will remain at the default setting.
Defaults are used throughout the computer industry to enable software to work 'out of the box' and not require ordinary people ('Users') to spend hours selecting every conceivable option in advance - quite thoughtful really!
Default Password
The password installed by a manufacturer and required to access a computer system when it is initially delivered, or a password required by software (typically shareware) to prove that the user is registered with the software vendor. Default passwords are not normally encountered on new PCs and have become relatively rare, but, in cases where such a password has been installed, the new owner of the equipment should change it at the earliest opportunity, to avoid it being known to third parties.
There are a range of default passwords known to everyone; and these are the first ones tried by anyone hacking into, or merely attempting opportunistic access. Such passwords as 'password', '123456' and ' ' i.e. blank (nothing) must be changed immediately. If you have one of these or similar passwords; please change it now. RUSecure™ will still be here when you have finished!
Denial of Service
A Denial of Service (DoS)attack, is an Internet attack against a Web site whereby a client is denied the level of service expected. In a mild case, the impact can be unexpectedly poor performance. In the worst case, the server can become so overloaded as to cause a crash of the system.
DoS attacks do not usually have theft or corruption of data as their primary motive and will often be executed by persons who have a grudge against the organisation concerned. The following are the main types of DoS attack :-
* Buffer Overflow Attacks; whereby data is sent to the server at a rate and volume that exceeds the capacity of the system; causing errors.
* SYN Attack. This takes places when connection requests to the server are not properly responded to, causing a delay in connection. Although these failed connection will eventually time out, should they occur in volume, they can deny access to other legitimate requests for access.
* Teardrop Attack. The exploitation of a features of the TCP/IP protocol whereby large packets of data are split into 'bite sized chunks' with each fragment being identified to the next by an 'offset' marker. Later the fragments are supposed to be re-assembled by the receiving system. In the teardrop attack, the attacker enters a confusing offset value in the second (or later) fragment which can crash the recipient's system.
* Smurf Attack or Ping Attack. This is where an illegitimate 'attention request' or Ping is sent to a system, with the return address being that of the target host (to be attacked). The intermediate system responds to the Ping request but responds to the unsuspecting victim system. If the receipt of such responses becomes excessive, the target system will be unable to distinguish between legitimate and illegitimate traffic.
* Viruses. Viruses are not usually targeted but where the host server becomes infected, it can cause a Denial of Service; or worse.
* Physical Attacks. A physical attack may be little more that cutting the power supply, or perhaps the removal of a network cable.
DES / AES
DES - The Data Encryption Standard and the AES - Advanced Encryption Standard are both data encryption standards for the scrambling of data to protect its confidentiality.
It was developed by IBM in co-operation with the American National Security Agency and published in 1974. It has become extremely popular and, because it used to be so difficult to break, with 72,000,000,000,000,000 possible key variations, was banned from export from the USA. However, restrictions by the US Government, on the export of encryption technology was lifted in 2000 to the countries of the EU and a number of other countries.
The AES - Advanced Encryption Standard, is a state of the art algorithm (developed by Rijndael) and chosen by the United States National Institute of Standards and Technology on October 2, 2000. Although selected, it will not become officially "approved" by the US Secretary of Commerce until Q2 2001. Meanwhile, products are already available which use the Rijndael algorithm within AES encryption tools. For example http://www.privatecrypt.com/int/.
Desktop
1. Verbal shorthand for Desktop Personal Computer, normally used to differentiate such a system from a 'Laptop' or portable PC.
2. In Windows 95®, and later releases, the screen visible on the computer monitor is known as the desktop and can be used to store programs and data as if it were a normal directory/folder. It is generally considered better practice to use the desktop as a place to store links to files and programs, rather than the files and programs themselves. This is partly because of the risk of accidental deletion, but - more importantly to companies - to avoid such files being visible to any curious passer-by.
Development Library
An area of the computer systems' fixed storage area which is set aside for the development of software, to minimise/avoid the possibility of conflict between an existing program and a new version.
Development Machine
An additional computer system, not part of the main processing system. Usually smaller than the main system, but similarly configured, the development machine is used for creating new software, amending existing software, and testing such creations and amendments to ensure that there is no possibility of the daily work and security of the main system being compromised by conflict between different versions of the same program. The development machine may also be used as a contingency standby machine, in case of failure of the main system. Companies unable to justify the costs of duplicate machines should use a Development Library within a partitioned area of the main system.
DHTML
Dynamic HyperText Markup Language. Contrary to its name, DHTML is not a new version of HTML - the Hyper Text Markup Language used to generate Web pages. DHTML is the combination of several browser features which, together, permit a Web page to be more 'dynamic'. Dynamic in this sense means the ability for the Web page to change its look and features after the page has been loaded; perhaps dependent upon the selection of various options. The recent versions of the most popular Web browsers all offer DHTML support.
Digital
Employing the binary system of numbers (1 and 0 only) for processing purposes.
Digital Certificate
A digital certificate is the electronic version of an ID card that establishes your credentials and authenticates your connection when performing e-Commerce transactions over the Internet, using the World Wide Web.
To obtain Digital Certificate an organisation must apply to a Certification Authority which is responsible for validating and ensuring the authenticity of requesting organisation. The Certificate will identify the name of the organisation, a serial number, the validity date ("from / to") and the organisation's Public Key where encryption to / from that organisation is required.
In addition, the Digital Certificate will also contain the Digital Signature of the Certification Authority to allow any recipient to confirm the authenticity of the Digital Certificate.
A global standard (X. 509 Public Key Infrastructure for the Internet) defines the requirements for Digital Certificates and the major Certificate Authorities conform to this. Such standards, and the integrity of the Certificate Authorities are vital for the establishment of 'digital trust', without which e-Commerce will never attain its potential.
Digital Signature
A digital signature is an electronic equivalent of an individual's signature. It authenticates the message to which it is attached and validates the authenticity of the sender. In addition, it also provides confirmation that the contents of the message to which it is attached, have not been tampered with, en route from the sender to the receiver.
A further feature is that an e-mail 'signed' with a digital signature cannot easily be repudiated; i.e. the sender is not able to deny the sending and the contents of the message; plus it provides a digital time stamp to confirm the time and date of transmission.
For a digital signature to be recognised, and acknowledged as something of integrity, it needs to be trusted by the recipient. It is for this reason that a Certification Authority will supply a digital signature to persons, the identity of whom, it has been able to verify; perhaps by having an Attorney's stamp on a document which validates the applicant's name, address, date of birth etc.
To provide greater digital trust, the Digital Signature is packaged with the certificate of the Certification Authority, and this too may be inspected for validity and expiration.
Most people expect digital signatures to totally replace the use of the ('old fashioned') pen and ink signature with orders and authorities being accepted via digitally signed e-mails, the contents of which may, or may not, be encrypted for additional security.
N.B. In July 2000, Digital Signatures became legally accepted in the United Kingdom under Section 7 of the Electronic Communications Act. In the USA also, Congress approved the use of Digital Signatures for certain types of e-Business around the same time under the E-Sign Act. Because both Acts are extremely new, it is strongly recommended that legal advice be sought before reliance is placed upon this new legislation.
Digital Versatile Disk - DVD
Currently, these optical storage disks are being pioneered by the entertainment business; notably because the DVD is able to store a full length feature movie on a single CD size disk, with faithful reproduction of visual and audio quality.
DVD, with a capacity (using both sides of the disk) of approx. 17GB, will doubtless replace the present CDs / CD-ROMs with their 'modest' 670MB capacity. At present consumer models are read only, but they will soon offer full record capability with integration into information systems.
Digital Watermark
A unique identifier that becomes part of a digital document and cannot be removed. The watermark is invisible to the human eye but a computer can analyse the document and extract the hidden data. Digital watermarks are being used for Classified/Top Secret documents - usually Military/Governmental - and highly confidential commercial material. The primary use of such marks is to allow different marks to be used when the document is copied to different persons and thereby establish an Audit Trail should there be any leakage of information.
Disable
The process by which hardware or software is deliberately prevented from functioning in some way. For hardware, it may be as simple as switching off a piece of equipment, or disconnecting a cable. It is more commonly associated with software, particularly shareware or promotional software, which has been supplied to a user at little or no cost, to try before paying the full purchase or registration fee. Such software may be described as 'crippled' in that certain functions, such as saving or printing files are not permitted. Some in-house development staff may well disable parts of a new program, so that the user can try out the parts which have been developed, while work continues on the disabled functions.
Disabling is also often used as a security measure, for example the risk of virus infection through the use of infected floppy diskettes can be greatly reduced, by disconnecting a cable within the PC, thereby disabling the floppy drive. Even greater protection is achieved by removing the drive altogether, thereby creating a diskless PC.
Disaster Recovery Plan - DRP
The master plan needed by technical and non-technical staff to cope with a major problem - such as the Boeing Syndrome. Do not confuse and merge the DRP with the Business Continuity Plan. The DRP is the plan which is activated when there is an emergency. It is the plan which ensures that health and safety come first followed by damage limitation. Having contained the impact of the disaster, and having ensured that the situation is now under control e.g. through the Emergency Services, then the Business Continuity Plan will be activated.
One of the most difficult aspects of a DRP is agreeing when it should be activated. In some circumstances it will be clear. For example, a tornado destroys part of the office block; or a serious fire reduces the premises to ashes. However, on many occasions, disasters have multiple warnings or indicators, and it is these which need to be considered and identified as the triggers to invoke your DRP.
N.B. The skills required to prepare and manage a DRP are not necessarily the same as those required for a Business Continuity Plan.
Distributed Processing
Spreading the organisation's computer processing load between two or more computers, often in geographically separate locations. If a organisation has the necessary financial and technical resources, distributed processing, with mirroring between sites, is an excellent contingency plan for sudden disasters.
Even if there is a total loss of one system, the remaining computer(s) can carry the load without disruption to users and without loss or corruption of data.
DMZ
A DMZ - De-Militarised Zone, is a separate part of an organisation's network which is shielded and 'cut off ' from the main corporate network and its systems. The DMZ contains technical equipment to prevent access from external parties (say on the Internet) from gaining access to your main systems.
The term comes from the buffer zone that was set up between North Korea and South Korea following their war in the early 1950s. A DMZ is not a single security component; it signifies a capability. Within the DMZ will be found firewalls, choke and access routers, front-end and back-end servers. Essentially, the DMZ provides multi-layer filtering and screening to completely block off access to the corporate network and data. And, even where a legitimate and authorised external query requests corporate data, no direct connection will be permitted from the external client, only a back-end server will issue the request (which may require additional authentication) from the internal corporate network.
However, the extent to which you permit corporate data to be accessible from and by external sources will depend upon the value of the Business Assets which could be placed at (additional) risk by allowing access to (even) pre-specified data types.
DNS
Domain Name System (or Server). The DNS is the means by which user friendly Web addresses are translated into arcane IP addresses. The DNS ensures that your are routed to the correct site.
Domain Name
The domain name identifies the location of an organisation or entity on the Internet and, through Domain Name Service translates this to an IP Address, which is the real address to which traffic destined for that domain name is routed.
Dongle
A mechanical device used by software developers to prevent unlicenced use of their product. Typically, a Dongle is a small connector plug, supplied with the original software package, which fits into a socket on a PC - usually a parallel port, also known generally as the LPT1 Printer port. Without the Dongle present, the software will not run. Some older Dongles act as a terminator, effectively blocking the port for any other use, but later versions have a pass-through function, allowing a printer to be connected at the same time. Even though the PC can still communicate with the printer, there have been problems with more recent printers which use active two-way communications with the PC to notify printing status, ink levels, etc.
Down
In IT terms, when a system is down, it is not available to users. This is not necessarily due to hardware or software faults, it may well be necessary to disconnect non-IT users, or take the system down for maintenance, installation of new hardware, loading new software etc. Traditionally such activities would take place after the End of Day, but the advent of 24x7 processing means there is no natural break in the cycle, and IT staff will therefore schedule the work for the time of minimum system workload - probably around 03:00 on Sunday morning!
Downtime
The amount of time a system is down in a given period. This will include crashes and system problems as well as scheduled maintenance work. Obviously, downtime impacts upon system availability, and most IT departments will maintain a downtime log to record when, and why, the system was not available to users. This log should be reviewed at intervals to identify any recurring problems, failure patterns etc.
DPI
Dots Per Inch. A measure of resolution for equipment such as printers and scanners. The more the better.
Drill Down
Descending through numerous layers of consolidations, summaries, etc., etc., to reach the really detailed information at the bottom.
Driver
A driver is a small interface program which allows a computer to communicate with a peripheral device, such as a printer or a scanner. The driver will be automatically installed when you connect the device to the PC; hence the need for a CD-ROM or floppy disk when installing such peripherals.
Dual Control
A control procedure whereby the active involvement of two people is required to complete a specified process. Such control may be physical; e.g. two persons required to unlock the Data Safe, or logical; as in the case of a higher level authorisation password required to permit the entry of data created or amended by another person.
Dual Control is one of the foundations of Information Security as it is based upon the premise that, for a breach to be committed, then both parties would need to be in collusion and, because one should always alternate the pairs of people, it would require a much greater level of corruption in order to breach dual control procedures; especially is such procedures require nested dual control access, such that (say) 2 pairs of people are required to enable access.
If this procedure appears someone 'dated' in today's 21st century 'wired' environment, please note that in 2000 a number of vendors started to sell 'Trusted Operations Systems', which enforce the requirement for dual control and the separation of duties, to provide substantially greater Information Security.
Dumb Terminal
A type of terminal that consists of a keyboard and a display screen that can be used to enter and transmit data to, or display data from, a computer to which it is connected. A dumb terminal, in contrast to an intelligent terminal, or PC, has no independent processing or storage capability and thus cannot function as a stand-alone device.
e-
Widely used - now widely overused - abbreviated prefix indicating 'electronic'.
Given the current frenzy for on-line services, companies are sticking the 'e-' prefix onto the front of almost any word to show how progressive and technologically advanced they are :-
e-business, e-commerce, e-trading, e-finance, e-broking, e-shopping, e-retailing, e-money, e-cash, e-purse, e-wallet, - the list is (probably) endless.
Earwigging
Alternative (slang) term for Eavesdropping.
Eavesdropping
Listening to someone else's conversation. In its most basic form, it amounts to one person keeping within earshot of a conversation between two other persons, but in the security and IT worlds it extends to remote listening and recording devices, include the interception of telephone calls, fax transmissions, e-mails, data transmissions, data-scoping, and even radio scanning for mobile communications.
The security implications for companies are primarily that user identification details or passwords can become known to criminally inclined individuals, or that confidential/sensitive information about the organisation, its finances, or activity plans may leak to competitors.
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e-Commerce
e-Commerce, e-Business or e-Tailing is an electronic transaction, performed over the Internet - and usually via the World Wide Web - in which the parties to the transaction agree, confirm and initiate both payment and goods transfer; at the click of the mouse.
There are two general types of e-Commerce activity; Business to Consumer (or Business to Customer) - B2C, and Business to Business - B2B.
Business to Consumer is usually, but not always, characterised by the purchase of goods or services, using the "shopping cart" metaphor and the acceptance of credit / debit cards in payment.
Business to Business, on the other hand, is concerned with using the Internet to place and receive orders from other businesses; establishing legally binding contractual commitments and pooling the resources of companies across the globe to tender for a project, with each party being authenticated and legally bound by their digital commitments.
However, to achieve this, and for e-Commerce to reach its true potential requires 'digital trust', and for this to take place requires strong technical tools to authenticate, encrypt and assure the confidentiality of data. Whilst e-Commerce can be initiated using e-mail, this requires the adoption of Digital Signatures which not only authenticates the sender, it also confirms the time and date of transmission and assures that the contents of the transmission were not tampered with.
Transactions initiated using Web servers, usually rely upon Digital Certificates and the use of the Secure Sockets Layer authentication and encrypted communication standard. In addition, to provide security for the secure transmission of documents, and other data, the use of the RSA standard is common, with Public Key Infrastructure (PKI) being used to create, issue and manage the use of public and private keys (or Digital Certificates).
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Editor
A program which allows a user to create, view, and amend, the contents of certain types of files. There are several types of editors, the most common being Text Editors, and Hex (Hexadecimal) Editors.
Editors work at the lowest level, either in ASCII (Text Editor) or directly with disk contents (Hex Editor).
Although text Editors, e.g. Notepad in Windows®, are common, companies should give consideration to staff access to Editors, particularly the more powerful types - such as Hex Editors. A Hex Editor can do considerable damage to the contents of computer files, which may not be recoverable.
NB, Although Word Processors and other programs can be used to edit their own files, they are NOT Editors in this context.
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Electronic Eavesdropping
Electronic eavesdropping is the intentional surveillance of data - voice, data, fax, e-mail, mobile telephones etc, often for nefarious purposes.
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End User
Usually reduced simply to User. The person who actually uses the hardware or software that has been developed for a specific task
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End User License Agreement - EULA
The End User License Agreement - or EULA - is a legally binding contract between the developer or publisher of a software program (or application) and the purchaser of that software. However, unlike the purchase of goods or services, the EULA is, as its name implies, a license agreement. In other words, the purchaser does not own the software, they merely have a right to use it in accordance with the licence agreement.
During the install of package software, the purchaser is shown the contents of the EULA and is often required to scroll down through the EULA, at the bottom of which, one may Accept or Refuse the terms of the EULA. By enforcing the need to scroll through the EULA, a user would be unlikely to succeed in any action to deny acceptance of the terms of the EULA.
In some cases, the EULA is written on the outside of the packaging with the breaking of the seal to the CD, indicating acceptance of the EULA.
In all cases, the EULA is the contract which users ignore at their peril; and whilst most EULAs contains broadly similar clauses and restrictions, it is important to confirm these before committing your organisation.
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Enforced Path
Normally, a user with the appropriate access control, is able to use any PC or workstation on the local area network to run an application or access certain data. However, where such data or system is classified as sensitive or requires restricted physical access, an enforced path may be applied. This is a straightforward configuration setting, performed by the Systems Administrator, whereby access is restricted to a specific workstation or range of workstations.
Enforcing the path will provide added security because it reduces the risk of unauthorised access; especially where such a workstation is itself within a secure zone, requiring physical access codes / keys etc.
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Enhancement
In theory, an improvement in hardware or software over the current version. In practice, enhancements are often merely vehicles to introduce some 'new' features into a package before withdrawing support for the current product, thereby pushing users towards upgrading their systems - at a price.
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Error Log
An error log records any abnormal activity on application software, usually in simple / plain text (ASCII). Each (main) application generates its own logs, and it is the responsibility of Systems Operations to retrieve and scrutinise them for any processing errors.
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Escrow
A legal provision whereby, in the event of a developer/supplier failing or otherwise ceasing to trade, the source code for their packaged software is made available to licensed / registered users, thereby enabling its ongoing maintenance.
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Extranet
An Extranet is a private network which uses the Internet protocols and extends beyond an organisation's premises, typically to allow access by clients, suppliers, or selected third parties.
Extranets require strong security if they are to prevent unauthorised access. This can range from a relatively simple User ID and password to the use of Digital Certificates, User IDs and passwords, with, naturally, end to end encryption of data.
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Fallback procedures
Fallback procedures are particular business procedures and measures, undertaken when events have triggered the execution of either a Business Continuity Plan or a Contingency Plan.
---------------------------------
Features / Glitches (Bugs)
Within the IT community, the term 'bug' is frowned upon, and is often replaced with the quaint term 'feature' or, a 'glitch'. Irrespective of how it is described, it remains a Bug !
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Fire Fighters
Net users who attempt to put out, or at least damp down, Flames/Flame Wars before they get out of hand. Rarely successful.
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Fire-Resistant Storage Cabinet
The legal records and documents of most organisations are likely to be in traditional paper / printer form. A fire resistant cabinet or safe is required tTo secure these documents from fire for a guaranteed period of time.
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Firewalls
Firewalls are security devices used to restrict access in communication networks. They prevent computer access between networks (say from the Internet to your corporate network), and only allow access to services which are expressly registered. They also keep logs of all activity, which may be used in investigations.
With the rapid growth in electronic communications - particularly via the Internet - firewalls, and firewall software, are being installed which will allow remote users to access limited parts of the system but restrict further access without satisfying specific identification and authorisation requirements. For example; an organisations' Web site will contain pages which are available to any Internet 'surfer' but other areas will not be accessible without recognition of authorised user status by the system. See Extranet.
Firewall Machine. A dedicated gateway computer with special security precautions on it, used to service outside network, especially Internet, connections and dial-in lines. The idea is to protect a cluster of more loosely administered machines hidden behind it from intrusion. The typical firewall is an inexpensive microprocessor-based Unix machine with no critical data, with modems and public network ports on it, but just one carefully watched connection back to the rest of the cluster. The special precautions may include threat monitoring, call-back, and even a complete iron box which can be keyed to particular incoming IDs or activity patterns.
Firewall Code. The code put in a system (say, a telephone switch) to make sure that the users can't do any damage. Since users always want to be able to do everything but never want to suffer for any mistakes, the construction of a firewall is a question not only of defensive coding but also of interface presentation, so that users don't even get curious about those corners of a system where they can burn themselves.
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Fit for Purpose
Fit for Purpose is a general expression which can be useful to ensure that Information Security solutions are appropriate for your organisation. Vendors will sometimes attempt to 'fit' their solution to your problem. Fit for Purpose is an expression which, when used within the solution negotiation context, places an onus of responsibility upon the vendor to ensure that its solution is (indeed) fit for the purpose which their client expects.
Example : a well known systems company contracted for the sale of their system. Inclusive in the price was one of week training in the system. During implementation it became apparent that one week for training was totally inadequate. The customer successfully claimed (prior to legal action) that the supplier's solution was inadequate and hence not fit for purpose.
When considering Information Security solutions, it is good practice to remind any potential suppliers in your requirement that the solution must be fit for purpose. See also Request For Proposal.
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Fix
An operational expedient that may be necessary if there is an urgent need to amend or repair data, or solve a software bug problem.
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Fixed Storage
The internal media used by a computer to store files, data, programs etc, and usually referred to as the Fixed Disk(s) or Hard Drive(s). Fixed storage devices obviously can be removed from the system for repair, maintenance, upgrade etc., but generally this cannot be done without a toolkit to open up the system for physical access by an engineer. The term is used mainly to differentiate these items from removable storage media such as tapes, floppy diskettes, CDs, etc.
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Flag
A message indication, sometimes, but not always, a warning to a user, which appears when a certain event takes place. For example, an inventory monitoring program may well 'flag' certain products when stocks fall below a predetermined level, to alert the user to re-order.
An alternative use is to warn of an event which will take place in the future, but has not yet occurred, for example, a financial institution aware of large cheque-based transaction on a customer's account may 'flag' the account to avoid an unauthorised overdraft.
Flags may be generated manually or automatically, depending on circumstances. In the case of the stock monitoring this would be automatic, while the cheque transaction example would be processed manually.
Automatic flags serve a useful purpose in drawing users' attention to situations which otherwise may be overlooked.
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Flame
'Flame' is abusive communication by E-mail or posting to a newsgroup, which attacks an individual or organisation for some real or imagined grievance. The real problem is broader than that of a few rude e-mails: flame represents the anarchistic side of the Internet. The flame may start with only one abusive message, but it is broadcast so widely that large numbers of unconnected browsers join in - often on both sides of the argument. This can lead to 'Flame Wars', where the traffic load becomes so high that communications network performance degrades, and E-mail boxes become blocked - as is the case with bottlenecking and mail bombing.
Problems for companies may arise if a member of staff has used an organisation's e-mail address to start the flame - another reason to monitor staff activities.
Flame has some redeeming features. Deeply unpleasant (or disturbed) individuals who posted lengthy racist (or sexist, or some other -ist) diatribes have found themselves flamed off the Net....
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Flame Bait
A Usenet posting or other message intended to trigger a flame war, or one that invites flames in reply. Acceptable for Usenet posters on a domestic machine, but not recommended in the office!
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Flash
Two meanings. Firstly, Similar to a Flag but more obvious and usually more urgent, or more serious, a Flash is a visual warning to a user, often associated with security control procedures. For example, if a user who is already logged on at one computer attempts to also log on at a second terminal, the system will Flash the IT supervisor console to warn of possible attempted breach of security.
Secondly; Flash is a technology being used to provide complex animation and sound on Web sites. It is extremely popular!
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Wednesday, August 31, 2011
Sample Archive log command file for VMS
Sample Archive log command file for VMS:
----------------------------------------
$ dup = "backup/ignore=(noback,interl,label)/log"
$ sqldba
CONNECT INTERNAL
alter tablespace system begin backup;
exit
$ dup u01:[oracle]ora_system.dbs tape1:ora_system.bck/sav
$ sqldba
CONNECT INTERNAL
alter tablespace system end backup;
alter tablespace appl1 begin backup;
exit
$ dup u02:[oracle]appl1.dbs tape1:appl1.bck/sav
$ sqldba
CONNECT INTERNAL
alter tablespace appl1 end backup;
exit
$!
$! get archive logs
$ rename/log u03:[oracle.arcs]*.arc *.arclogs
$ rename/log u04:[oracle.arcs2]*.arc *.arclogs !secondary arcs dir
$ sqldba
CONNECT INTERNAL
alter system switch logfile;
exit
$ dup u03:[oracle.arcs]*.arclogs,u04:[oracle.arcs2]*.arclogs
tape1:logs.bck/sav
$ del/log u03:[oracle.arcs]*.arclogs;0
$ del/log u04:[oracle.arcs2]*.arclogs;0
$!
$! get control file
$ sqldba
CONNECT INTERNAL
alter database backup controlfile to 'u01:[oracle]control.bkp' reuse;
exit
$ dup u01:[oracle]control.bkp tape1:control.bck/sav
Note: The "alter system switch logfile" command is all but undocumented,
(see pg 3-15 of the DBA guide. It refers you to a nonexistent
cross-reference). It will NOT show up in the alert log. Don't
be alarmed by that; it does actually work.
----------------------------------------
$ dup = "backup/ignore=(noback,interl,label)/log"
$ sqldba
CONNECT INTERNAL
alter tablespace system begin backup;
exit
$ dup u01:[oracle]ora_system.dbs tape1:ora_system.bck/sav
$ sqldba
CONNECT INTERNAL
alter tablespace system end backup;
alter tablespace appl1 begin backup;
exit
$ dup u02:[oracle]appl1.dbs tape1:appl1.bck/sav
$ sqldba
CONNECT INTERNAL
alter tablespace appl1 end backup;
exit
$!
$! get archive logs
$ rename/log u03:[oracle.arcs]*.arc *.arclogs
$ rename/log u04:[oracle.arcs2]*.arc *.arclogs !secondary arcs dir
$ sqldba
CONNECT INTERNAL
alter system switch logfile;
exit
$ dup u03:[oracle.arcs]*.arclogs,u04:[oracle.arcs2]*.arclogs
tape1:logs.bck/sav
$ del/log u03:[oracle.arcs]*.arclogs;0
$ del/log u04:[oracle.arcs2]*.arclogs;0
$!
$! get control file
$ sqldba
CONNECT INTERNAL
alter database backup controlfile to 'u01:[oracle]control.bkp' reuse;
exit
$ dup u01:[oracle]control.bkp tape1:control.bck/sav
Note: The "alter system switch logfile" command is all but undocumented,
(see pg 3-15 of the DBA guide. It refers you to a nonexistent
cross-reference). It will NOT show up in the alert log. Don't
be alarmed by that; it does actually work.
Tuesday, August 16, 2011
DB2 INTERVIEW QUESTIONS
DB2 INTERVIEW QUESTIONS
1) How would you find out the total number of rows in a DB2 table?
Use SELECT COUNT(*) ... in db2 query
2) How do you eliminate duplicate values in DB2 SELECT ?
Use SELECT DISTINCT ... in db2 query
3) How do you select a row using indexes in DB2?
Specify the indexed columns in the WHERE clause of db2 query.
4) How do you find the maximum value in a column in db2?
Use SELECT MAX(...) .. in db2 query
5) How do you retrieve the first 5 characters of FIRSTNAME column of DB2 table EMP ?
SQL Query : SELECT SUBSTR(FIRSTNAME,1,5) FROM EMP;
6) What are aggregate functions?
Bulit-in mathematical functions for use in SELECT clause.
7) Can you use MAX on a CHAR column?
YES.
8) My SQL statement SELECT AVG(SALARY) FROM EMP yields inaccurate results. Why?
Because SALARY is not declared to have NULLs and the employees for whom the salary is not known are also counted.
9) How do you concatenate the FIRSTNAME and LASTNAME from EMP table to give a complete name?
SELECT FIRSTNAME || ‘ ‘ || LASTNAME FROM EMP;
10) What is the use of VALUE function?
1. Avoid -ve SQLCODEs by handling nulls and zeroes in computations
2. Substitute a numeric value for any nulls used in computation
11) What is UNION,UNION ALL? –
UNION : eliminates duplicates
UNION ALL: retains duplicates
Both these are used to combine the results of different SELECT statements.
Suppose I have five SQL SELECT statements connected by UNION/UNION ALL, how many times should I specify UNION to eliminate the duplicate rows? -
Once.
12) What is the restriction on using UNION in embedded SQL?
It has to be in a CURSOR.
13) In the WHERE clause what is BETWEEN and IN? –
BETWEEN supplies a range of values while IN supplies a list of values.
14) Is BETWEEN inclusive of the range values specified? –
Yes.
15) What is 'LIKE' used for in WHERE clause? What are the wildcard characters? –
LIKE is used for partial string matches. ‘%’ ( for a string of any character ) and ‘_’ (for any single character ) are the two wild card characters.
16) When do you use a LIKE statement?
To do partial search e.g. to search employee by name, you need not specify the complete name; using LIKE, you can search for partial string matches.
17) What is the meaning of underscore ( ‘_’ ) in the LIKE statement? –
Match for any single character.
18) What do you accomplish by GROUP BY ... HAVING clause? –
GROUP BY partitions the selected rows on the distinct values of the column on which you group by.
HAVING selects GROUPs which match the criteria specified
19) Consider the employee table with column PROJECT nullable. How can you get a list of employees who are not assigned to any project?
SELECT EMPNO
FROM EMP
WHERE PROJECT IS NULL;
20) What is the result of this query if no rows are selected:
SELECT SUM(SALARY)
FROM EMP
WHERE QUAL=‘MSC’;
NULL
21) Why SELECT * is not preferred in embedded SQL programs?
For three reasons:
If the table structure is changed ( a field is added ), the program will have to be modified
Program might retrieve the columns which it might not use, leading on I/O over head.
The chance of an index only scan is lost.
What are correlated subqueries? -
A subquery in which the inner ( nested ) query refers back to the table in the outer query. Correlated subqueries must be evaluated for each qualified row of the outer query that is referred to.
22) What are the issues related with correlated subqueries? –
???
23) What is a cursor? why should it be used? –
Cursor is a programming device that allows the SELECT to find a set of rows but return them one at a time.
Cursor should be used because the host language can deal with only one row at a time.
24) How would you retrieve rows from a DB2 table in embedded SQL? –
Either by using the single row SELECT statements, or by using the CURSOR.
Apart from cursor, what other ways are available to you to retrieve a row from a table in embedded SQL? -
Single row SELECTs.
25) Where would you specify the DECLARE CURSOR statement? –
See answer to next question.
26) How do you specify and use a cursor in a COBOL program? –
Use DECLARE CURSOR statement either in working storage or in procedure division(before open cursor), to specify the SELECT statement. Then use OPEN, FETCH rows in a loop and finally CLOSE.
27) What happens when you say OPEN CURSOR?
If there is an ORDER BY clause, rows are fetched, sorted and made available for the FETCH statement. Other wise simply the cursor is placed on the first row.
28) Is DECLARE CURSOR executable?
No.
29) Can you have more than one cursor open at any one time in a program ? –
Yes.
30) When you COMMIT, is the cursor closed? - drona questions
Yes.
31) How do you leave the cursor open after issuing a COMMIT? ( for DB2 2.3 or above only )
Use WITH HOLD option in DECLARE CURSOR statement. But, it has not effect in psuedo-conversational CICS programs.
32) Give the COBOL definition of a VARCHAR field.
A VARCHAR column REMARKS would be defined as follows:
...
10 REMARKS.
49 REMARKS-LEN PIC S9(4) USAGE COMP.
49 REMARKS-TEXT PIC X(1920).
33) What is the physical storage length of each of the following DB2 data types:
DATE, TIME, TIMESTAMP?
DATE: 4bytes
TIME: 3bytes
TIMESTAMP: 10bytes
34) What is the COBOL picture clause of the following DB2 data types:
DATE, TIME, TIMESTAMP?
DATE: PIC X(10)
TIME : PIC X(08)
TIMESTAMP: PIC X(26)
35) What is the COBOL picture clause for a DB2 column defined as DECIMAL(11,2)? - Ramesh
PIC S9(9)V99 COMP-3.
Note: In DECIMAL(11,2), 11 indicates the size of the data type and 2 indicates the precision.
36) What is DCLGEN ? -
DeCLarations GENerator: used to create the host language copy books for the table definitions. Also creates the DECLARE table.
37) What are the contents of a DCLGEN? -
1. EXEC SQL DECLARE TABLE statement which gives the layout of the table/view in terms of DB2 datatypes.
2. A host language copy book that gives the host variable definitions for the column names.
38) Is it mandatory to use DCLGEN? If not, why would you use it at all? -
It is not mandatory to use DCLGEN.
Using DCLGEN, helps detect wrongly spelt column names etc. during the pre-compile stage itself ( because of the DECLARE TABLE ). DCLGEN being a tool, would generate accurate host variable definitions for the table reducing chances of error.
39) Is DECLARE TABLE in DCLGEN necessary? Why it used?
It not necessary to have DECLARE TABLE statement in DCLGEN. This is used by the pre-compiler to validate the table-name, view-name, column name etc., during pre-compile.
40) Will precompile of an DB2-COBOL program bomb, if DB2 is down?
No. Because the precompiler does not refer to the DB2 catalogue tables.
41) How is a typical DB2 batch pgm executed ?
1. Use DSN utility to run a DB2 batch program from native TSO. An example is shown:
DSN SYSTEM(DSP3)
RUN PROGRAM(EDD470BD) PLAN(EDD470BD) LIB('ED 01T.OBJ.LOADLIB')
END
2. Use IKJEFT01 utility program to run the above DSN command in a JCL.
Assuming that a site’s standard is that pgm name = plan name, what is the easiest way to find out which pgms are affected by change in a table’s structure ?
Query the catalogue tables SYSPLANDEP and SYSPACKDEP.
42) Name some fields from SQLCA.
SQLCODE, SQLERRM, SQLERRD
43) How can you quickly find out the # of rows updated after an update statement?
Check the value stored in SQLERRD(3).
44) What is EXPLAIN? – drona questions
EXPLAIN is used to display the access path as determined by the optimizer for a SQL statement. It can be used in SPUFI (for single SQL statement ) or in BIND step (for embedded SQL ).
45) What do you need to do before you do EXPLAIN?
Make sure that the PLAN_TABLE is created under the AUTHID.
46) Where is the output of EXPLAIN stored? –
In userid.PLAN_TABLE
47) EXPLAIN has output with MATCHCOLS = 0. What does it mean? –
a nonmatching index scan if ACCESSTYPE = I.
48) How do you do the EXPLAIN of a dynamic SQL statement?
1. Use SPUFI or QMF to EXPLAIN the dynamic SQL statement
2. Include EXPLAIN command in the embedded dynamic SQL statements
49) How do you simulate the EXPLAIN of an embedded SQL statement in SPUFI/QMF? Give an example with a host variable in WHERE clause.)
Use a question mark in place of a host variable ( or an unknown value ). e.g.
SELECT EMP_NAME
FROM EMP
WHERE EMP_SALARY > ?
50) What are the isolation levels possible ? –
CS: Cursor Stability
RR: Repeatable Read
51) What is the difference between CS and RR isolation levels?
CS: Releases the lock on a page after use
RR: Retains all locks acquired till end of transaction
52) Where do you specify them ?
ISOLATION LEVEL is a parameter for the bind process.
53) When do you specify the isolation level? How?
During the BIND process. ISOLATION ( CS/RR )...
I use CS and update a page. Will the lock be released after I am done with that page?
No.
54) What are the various locking levels available?
PAGE, TABLE, TABLESPACE
55) How does DB2 determine what lock-size to use?
1. Based on the lock-size given while creating the tablespace
2. Programmer can direct the DB2 what lock-size to use
3. If lock-size ANY is specified, DB2 usually chooses a lock-size of PAGE
56) What are the disadvantages of PAGE level lock? - RAMESH www.geocities.com/srcsinc
High resource utilization if large updates are to be done
57) What is lock escalation?
Promoting a PAGE lock-size to table or tablespace lock-size when a transaction has acquired more locks than specified in NUMLKTS. Locks should be taken on objects in single tablespace for escalation to occur.
58) What are the various locks available?
SHARE, EXCLUSIVE, UPDATE
59) Can I use LOCK TABLE on a view?
No. To lock a view, take lock on the underlying tables.
60) What is ALTER ? –
SQL command used to change the definition of DB2 objects
61) What is a DBRM, PLAN ?
DBRM: DataBase Request Module, has the SQL statements extracted from the host language program by the pre-compiler.
PLAN: A result of the BIND process. It has the executable code for the SQL statements in the DBRM.
62) What is ACQUIRE/RELEASE in BIND?
Determine the point at which DB2 acquires or releases locks against table and tablespaces, including intent locks.
63) What else is there in the PLAN apart from the access path? –
PLAN has the executable code for the SQL statements in the host program
64) What happens to the PLAN if index used by it is dropped?
Plan is marked as invalid. The next time the plan is accessed, it is rebound.
65) What are PACKAGES ? –
They contain executable code for SQL statements for one DBRM.
66) What are the advantages of using a PACKAGE?
1. Avoid having to bind a large number of DBRM members into a plan
2. Avoid cost of a large bind
3. Avoid the entire transaction being unavailable during bind and automatic rebind of a plan
4. Minimize fallback complexities if changes result in an error.
67) What is a collection?
a user defined name that is the anchor for packages. It has not physical existence. Main usage is to group packages.
In SPUFI suppose you want to select max. of 1000 rows , but the select returns only 200 rows.
68) What are the 2 sqlcodes that are returned? –
100 ( for successful completion of the query ), 0 (for successful COMMIT if AUTOCOMMIT is set to Yes).
69) How would you print the output of an SQL statement from SPUFI? –
Print the output dataset.
70) How do you pull up a query which was previously saved in QMF ? –
??
71) Lot of updates have been done on a table due to which indexes have gone haywire. What do you do? –
Looks like index page split has occurred. DO a REORG of the indexes.
72) What is dynamic SQL? –
Dynamic SQL is a SQL statement created at program execution time.
73) When is the access path determined for dynamic SQL? –
At run time, when the PREPARE statement is issued.
74) Suppose I have a program which uses a dynamic SQL and it has been performing well till now. Off late, I find that the performance has deteriorated. What happened? –
Probably RUN STATS is not done and the program is using a wrong index due to incorrect stats.
Probably RUNSTATS is done and optimizer has chosen a wrong access path based on the latest statistics.
75) How does DB2 store NULL physically?
as an extra-byte prefix to the column value. physically, the nul prefix is Hex ’00’ if the value is present and Hex ‘FF’ if it is not.
76) How do you retrieve the data from a nullable column? –
Use null indicators. Syntax ... INTO :HOSTVAR:NULLIND
77) What is the picture clause of the null indicator variable? –
S9(4) COMP.
78) What does it mean if the null indicator has -1, 0, -2? –
-1 : the field is null
0 : the field is not null
-2 : the field value is truncated
79) How do you insert a record with a nullable column?
To insert a NULL, move -1 to the null indicator
To insert a valid value, move 0 to the null indicator
80) What is RUNSTATS? –
A DB2 utility used to collect statistics about the data values in tables which can be used by the optimizer to decide the access path. It also collects statistics used for space management. These statistics are stored in DB2 catalog tables.
81) When will you chose to run RUNSTATS?
After a load, or after mass updates, inserts, deletes, or after REORG.
82) Give some example of statistics collected during RUNSTATS?
# of rows in the table
Percent of rows in clustering sequence
# of distinct values of indexed column
# of rows moved to a nearby/farway page due to row length increase
83) What is REORG? When is it used?
REORG reorganizes data on physical storage to reclutser rows, positioning overflowed rows in their proper sequence, to reclaim space, to restore free space. It is used after heavy updates, inserts and delete activity and after segments of a segmented tablespace have become fragmented.
84) What is IMAGECOPY ? –
It is full backup of a DB2 table which can be used in recovery.
85) When do you use the IMAGECOPY? –
To take routine backup of tables
After a LOAD with LOG NO
After REORG with LOG NO
86) What is COPY PENDING status?
A state in which, an image copy on a table needs to be taken, In this status, the table is available only for queries. You cannot update this table. To remove the COPY PENDING status, you take an image copy or use REPAIR utility.
87) What is CHECK PENDING ?
When a table is LOADed with ENFORCE NO option, then the table is left in CHECK PENDING status. It means that the LOAD utility did not perform constraint checking.
88) What is QUIESCE?
A QUIESCE flushes all DB2 buffers on to the disk. This gives a correct snapshot of the database and should be used before and after any IMAGECOPY to maintain consistency.
89) What is a clustering index ? –
Causes the data rows to be stored in the order specified in the index. A mandatory index defined on a partitioned table space.
90) How many clustering indexes can be defined for a table?
Only one.
91) What is the difference between primary key & unique index ?
Primary : a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table.
92) What is sqlcode -922 ?
Authorization failure
93) What is sqlcode -811?
SELECT statement has resulted in retrieval of more than one row.
94) What does the sqlcode of -818 pertain to? –
This is generated when the consistency tokens in the DBRM and the load module are different.
95) Are views updateable ?
Not all of them. Some views are updateable e.g. single table view with all the fields or mandatory fields. Examples of non-updateable views are views which are joins, views that contain aggregate functions(such as MIN), and views that have GROUP BY clause.
96) If I have a view which is a join of two or more tables, can this view be updateable? –
No.
97) What are the 4 environments which can access DB2 ?
TSO, CICS, IMS and BATCH
98) What is an inner join, and an outer join ?
Inner Join: combine information from two or more tables by comparing all values that meet the search criteria in the designated column or columns of on e table with all the clause in corresponding columns of the other table or tables. This kind of join which involve a match in both columns are called inner joins.
Outer join is one in which you want both matching and non matching rows to be returned. DB2 has no specific operator for outer joins, it can be simulated by combining a join and a correlated sub query with a UNION.
99) What is FREEPAGE and PCTFREE in TABLESPACE creation?
PCTFREE: percentage of each page to be left free
FREEPAGE: Number of pages to be loaded with data between each free page
100) What are simple, segmented and partitioned table spaces ?
Simple Tablespace:
Can contain one or more tables
Rows from multiple tables can be interleaved on a page under the DBAs control and maintenance
Segmented Tablespace:
Can contain one or more tables
Tablespace is divided into segments of 4 to 64 pages in increments of 4 pages. Each segment is dedicated to single table. A table can occupy multiple segments
Partitioned Tablespace:
Can contain one table
Tablespace is divided into parts and each part is put in a separate VSAM dataset.
101) What is filter factor?
one divided by the number of distinct values of a column.
102) What is index cardinality? –
The number of distinct values a column or columns contain.
103) What is a synonym ?
Synonym is an alternate name for a table or view used mainly to hide the leading qualifier of a table or view.. A synonym is accessible only by the creator.
104) What is the difference between SYNONYM and ALIAS?
SYNONYM: is dropped when the table or tablespace is dropped. Synonym is available only to the creator.
ALIAS: is retained even if table or tablespace is dropped. ALIAS can be created even if the table does not exist. It is used mainly in distributed environment to hide the location info from programs. Alias is a global object & is available to all.
105) What do you mean by NOT NULL WITH DEFAULT? When will you use it?
This column cannot have nulls and while insertion, if no value is supplied then it wil have zeroes, spaces or date/time depending on whether it is numeric, character or date/time.
Use it when you do not want to have nulls but at the same time cannot give values all the time you insert this row.
106) What do you mean by NOT NULL? When will you use it?
The column cannot have nulls. Use it for key fields.
107) When would you prefer to use VARCHAR?
When a column which contains long text, e.g. remarks, notes, may have in most cases less than 50% of the maximum length.
108) What are the disadvantages of using VARCHAR?
1. Can lead to high space utilization if most of the values are close to maximum.
2. Positioning of VARCHAR column has to be done carefully as it has performance implications.
3. Relocation of rows to different pages can lead to more I/Os on retrieval.
109) How do I create a table MANAGER ( EMP#, MANAGER) where MANAGER is a foreign key which references to EMP# in the same table? Give the exact DDL.
First CREATE MANAGER table with EMP# as the primary key. Then ALTER it to define the foreign key.
When is the authorization check on DB2 objects done - at BIND time or run time?
At run time.
110) What is auditing?
Recording SQL statements that access a table. Specified at table creation time or through alter.
1) How would you find out the total number of rows in a DB2 table?
Use SELECT COUNT(*) ... in db2 query
2) How do you eliminate duplicate values in DB2 SELECT ?
Use SELECT DISTINCT ... in db2 query
3) How do you select a row using indexes in DB2?
Specify the indexed columns in the WHERE clause of db2 query.
4) How do you find the maximum value in a column in db2?
Use SELECT MAX(...) .. in db2 query
5) How do you retrieve the first 5 characters of FIRSTNAME column of DB2 table EMP ?
SQL Query : SELECT SUBSTR(FIRSTNAME,1,5) FROM EMP;
6) What are aggregate functions?
Bulit-in mathematical functions for use in SELECT clause.
7) Can you use MAX on a CHAR column?
YES.
8) My SQL statement SELECT AVG(SALARY) FROM EMP yields inaccurate results. Why?
Because SALARY is not declared to have NULLs and the employees for whom the salary is not known are also counted.
9) How do you concatenate the FIRSTNAME and LASTNAME from EMP table to give a complete name?
SELECT FIRSTNAME || ‘ ‘ || LASTNAME FROM EMP;
10) What is the use of VALUE function?
1. Avoid -ve SQLCODEs by handling nulls and zeroes in computations
2. Substitute a numeric value for any nulls used in computation
11) What is UNION,UNION ALL? –
UNION : eliminates duplicates
UNION ALL: retains duplicates
Both these are used to combine the results of different SELECT statements.
Suppose I have five SQL SELECT statements connected by UNION/UNION ALL, how many times should I specify UNION to eliminate the duplicate rows? -
Once.
12) What is the restriction on using UNION in embedded SQL?
It has to be in a CURSOR.
13) In the WHERE clause what is BETWEEN and IN? –
BETWEEN supplies a range of values while IN supplies a list of values.
14) Is BETWEEN inclusive of the range values specified? –
Yes.
15) What is 'LIKE' used for in WHERE clause? What are the wildcard characters? –
LIKE is used for partial string matches. ‘%’ ( for a string of any character ) and ‘_’ (for any single character ) are the two wild card characters.
16) When do you use a LIKE statement?
To do partial search e.g. to search employee by name, you need not specify the complete name; using LIKE, you can search for partial string matches.
17) What is the meaning of underscore ( ‘_’ ) in the LIKE statement? –
Match for any single character.
18) What do you accomplish by GROUP BY ... HAVING clause? –
GROUP BY partitions the selected rows on the distinct values of the column on which you group by.
HAVING selects GROUPs which match the criteria specified
19) Consider the employee table with column PROJECT nullable. How can you get a list of employees who are not assigned to any project?
SELECT EMPNO
FROM EMP
WHERE PROJECT IS NULL;
20) What is the result of this query if no rows are selected:
SELECT SUM(SALARY)
FROM EMP
WHERE QUAL=‘MSC’;
NULL
21) Why SELECT * is not preferred in embedded SQL programs?
For three reasons:
If the table structure is changed ( a field is added ), the program will have to be modified
Program might retrieve the columns which it might not use, leading on I/O over head.
The chance of an index only scan is lost.
What are correlated subqueries? -
A subquery in which the inner ( nested ) query refers back to the table in the outer query. Correlated subqueries must be evaluated for each qualified row of the outer query that is referred to.
22) What are the issues related with correlated subqueries? –
???
23) What is a cursor? why should it be used? –
Cursor is a programming device that allows the SELECT to find a set of rows but return them one at a time.
Cursor should be used because the host language can deal with only one row at a time.
24) How would you retrieve rows from a DB2 table in embedded SQL? –
Either by using the single row SELECT statements, or by using the CURSOR.
Apart from cursor, what other ways are available to you to retrieve a row from a table in embedded SQL? -
Single row SELECTs.
25) Where would you specify the DECLARE CURSOR statement? –
See answer to next question.
26) How do you specify and use a cursor in a COBOL program? –
Use DECLARE CURSOR statement either in working storage or in procedure division(before open cursor), to specify the SELECT statement. Then use OPEN, FETCH rows in a loop and finally CLOSE.
27) What happens when you say OPEN CURSOR?
If there is an ORDER BY clause, rows are fetched, sorted and made available for the FETCH statement. Other wise simply the cursor is placed on the first row.
28) Is DECLARE CURSOR executable?
No.
29) Can you have more than one cursor open at any one time in a program ? –
Yes.
30) When you COMMIT, is the cursor closed? - drona questions
Yes.
31) How do you leave the cursor open after issuing a COMMIT? ( for DB2 2.3 or above only )
Use WITH HOLD option in DECLARE CURSOR statement. But, it has not effect in psuedo-conversational CICS programs.
32) Give the COBOL definition of a VARCHAR field.
A VARCHAR column REMARKS would be defined as follows:
...
10 REMARKS.
49 REMARKS-LEN PIC S9(4) USAGE COMP.
49 REMARKS-TEXT PIC X(1920).
33) What is the physical storage length of each of the following DB2 data types:
DATE, TIME, TIMESTAMP?
DATE: 4bytes
TIME: 3bytes
TIMESTAMP: 10bytes
34) What is the COBOL picture clause of the following DB2 data types:
DATE, TIME, TIMESTAMP?
DATE: PIC X(10)
TIME : PIC X(08)
TIMESTAMP: PIC X(26)
35) What is the COBOL picture clause for a DB2 column defined as DECIMAL(11,2)? - Ramesh
PIC S9(9)V99 COMP-3.
Note: In DECIMAL(11,2), 11 indicates the size of the data type and 2 indicates the precision.
36) What is DCLGEN ? -
DeCLarations GENerator: used to create the host language copy books for the table definitions. Also creates the DECLARE table.
37) What are the contents of a DCLGEN? -
1. EXEC SQL DECLARE TABLE statement which gives the layout of the table/view in terms of DB2 datatypes.
2. A host language copy book that gives the host variable definitions for the column names.
38) Is it mandatory to use DCLGEN? If not, why would you use it at all? -
It is not mandatory to use DCLGEN.
Using DCLGEN, helps detect wrongly spelt column names etc. during the pre-compile stage itself ( because of the DECLARE TABLE ). DCLGEN being a tool, would generate accurate host variable definitions for the table reducing chances of error.
39) Is DECLARE TABLE in DCLGEN necessary? Why it used?
It not necessary to have DECLARE TABLE statement in DCLGEN. This is used by the pre-compiler to validate the table-name, view-name, column name etc., during pre-compile.
40) Will precompile of an DB2-COBOL program bomb, if DB2 is down?
No. Because the precompiler does not refer to the DB2 catalogue tables.
41) How is a typical DB2 batch pgm executed ?
1. Use DSN utility to run a DB2 batch program from native TSO. An example is shown:
DSN SYSTEM(DSP3)
RUN PROGRAM(EDD470BD) PLAN(EDD470BD) LIB('ED 01T.OBJ.LOADLIB')
END
2. Use IKJEFT01 utility program to run the above DSN command in a JCL.
Assuming that a site’s standard is that pgm name = plan name, what is the easiest way to find out which pgms are affected by change in a table’s structure ?
Query the catalogue tables SYSPLANDEP and SYSPACKDEP.
42) Name some fields from SQLCA.
SQLCODE, SQLERRM, SQLERRD
43) How can you quickly find out the # of rows updated after an update statement?
Check the value stored in SQLERRD(3).
44) What is EXPLAIN? – drona questions
EXPLAIN is used to display the access path as determined by the optimizer for a SQL statement. It can be used in SPUFI (for single SQL statement ) or in BIND step (for embedded SQL ).
45) What do you need to do before you do EXPLAIN?
Make sure that the PLAN_TABLE is created under the AUTHID.
46) Where is the output of EXPLAIN stored? –
In userid.PLAN_TABLE
47) EXPLAIN has output with MATCHCOLS = 0. What does it mean? –
a nonmatching index scan if ACCESSTYPE = I.
48) How do you do the EXPLAIN of a dynamic SQL statement?
1. Use SPUFI or QMF to EXPLAIN the dynamic SQL statement
2. Include EXPLAIN command in the embedded dynamic SQL statements
49) How do you simulate the EXPLAIN of an embedded SQL statement in SPUFI/QMF? Give an example with a host variable in WHERE clause.)
Use a question mark in place of a host variable ( or an unknown value ). e.g.
SELECT EMP_NAME
FROM EMP
WHERE EMP_SALARY > ?
50) What are the isolation levels possible ? –
CS: Cursor Stability
RR: Repeatable Read
51) What is the difference between CS and RR isolation levels?
CS: Releases the lock on a page after use
RR: Retains all locks acquired till end of transaction
52) Where do you specify them ?
ISOLATION LEVEL is a parameter for the bind process.
53) When do you specify the isolation level? How?
During the BIND process. ISOLATION ( CS/RR )...
I use CS and update a page. Will the lock be released after I am done with that page?
No.
54) What are the various locking levels available?
PAGE, TABLE, TABLESPACE
55) How does DB2 determine what lock-size to use?
1. Based on the lock-size given while creating the tablespace
2. Programmer can direct the DB2 what lock-size to use
3. If lock-size ANY is specified, DB2 usually chooses a lock-size of PAGE
56) What are the disadvantages of PAGE level lock? - RAMESH www.geocities.com/srcsinc
High resource utilization if large updates are to be done
57) What is lock escalation?
Promoting a PAGE lock-size to table or tablespace lock-size when a transaction has acquired more locks than specified in NUMLKTS. Locks should be taken on objects in single tablespace for escalation to occur.
58) What are the various locks available?
SHARE, EXCLUSIVE, UPDATE
59) Can I use LOCK TABLE on a view?
No. To lock a view, take lock on the underlying tables.
60) What is ALTER ? –
SQL command used to change the definition of DB2 objects
61) What is a DBRM, PLAN ?
DBRM: DataBase Request Module, has the SQL statements extracted from the host language program by the pre-compiler.
PLAN: A result of the BIND process. It has the executable code for the SQL statements in the DBRM.
62) What is ACQUIRE/RELEASE in BIND?
Determine the point at which DB2 acquires or releases locks against table and tablespaces, including intent locks.
63) What else is there in the PLAN apart from the access path? –
PLAN has the executable code for the SQL statements in the host program
64) What happens to the PLAN if index used by it is dropped?
Plan is marked as invalid. The next time the plan is accessed, it is rebound.
65) What are PACKAGES ? –
They contain executable code for SQL statements for one DBRM.
66) What are the advantages of using a PACKAGE?
1. Avoid having to bind a large number of DBRM members into a plan
2. Avoid cost of a large bind
3. Avoid the entire transaction being unavailable during bind and automatic rebind of a plan
4. Minimize fallback complexities if changes result in an error.
67) What is a collection?
a user defined name that is the anchor for packages. It has not physical existence. Main usage is to group packages.
In SPUFI suppose you want to select max. of 1000 rows , but the select returns only 200 rows.
68) What are the 2 sqlcodes that are returned? –
100 ( for successful completion of the query ), 0 (for successful COMMIT if AUTOCOMMIT is set to Yes).
69) How would you print the output of an SQL statement from SPUFI? –
Print the output dataset.
70) How do you pull up a query which was previously saved in QMF ? –
??
71) Lot of updates have been done on a table due to which indexes have gone haywire. What do you do? –
Looks like index page split has occurred. DO a REORG of the indexes.
72) What is dynamic SQL? –
Dynamic SQL is a SQL statement created at program execution time.
73) When is the access path determined for dynamic SQL? –
At run time, when the PREPARE statement is issued.
74) Suppose I have a program which uses a dynamic SQL and it has been performing well till now. Off late, I find that the performance has deteriorated. What happened? –
Probably RUN STATS is not done and the program is using a wrong index due to incorrect stats.
Probably RUNSTATS is done and optimizer has chosen a wrong access path based on the latest statistics.
75) How does DB2 store NULL physically?
as an extra-byte prefix to the column value. physically, the nul prefix is Hex ’00’ if the value is present and Hex ‘FF’ if it is not.
76) How do you retrieve the data from a nullable column? –
Use null indicators. Syntax ... INTO :HOSTVAR:NULLIND
77) What is the picture clause of the null indicator variable? –
S9(4) COMP.
78) What does it mean if the null indicator has -1, 0, -2? –
-1 : the field is null
0 : the field is not null
-2 : the field value is truncated
79) How do you insert a record with a nullable column?
To insert a NULL, move -1 to the null indicator
To insert a valid value, move 0 to the null indicator
80) What is RUNSTATS? –
A DB2 utility used to collect statistics about the data values in tables which can be used by the optimizer to decide the access path. It also collects statistics used for space management. These statistics are stored in DB2 catalog tables.
81) When will you chose to run RUNSTATS?
After a load, or after mass updates, inserts, deletes, or after REORG.
82) Give some example of statistics collected during RUNSTATS?
# of rows in the table
Percent of rows in clustering sequence
# of distinct values of indexed column
# of rows moved to a nearby/farway page due to row length increase
83) What is REORG? When is it used?
REORG reorganizes data on physical storage to reclutser rows, positioning overflowed rows in their proper sequence, to reclaim space, to restore free space. It is used after heavy updates, inserts and delete activity and after segments of a segmented tablespace have become fragmented.
84) What is IMAGECOPY ? –
It is full backup of a DB2 table which can be used in recovery.
85) When do you use the IMAGECOPY? –
To take routine backup of tables
After a LOAD with LOG NO
After REORG with LOG NO
86) What is COPY PENDING status?
A state in which, an image copy on a table needs to be taken, In this status, the table is available only for queries. You cannot update this table. To remove the COPY PENDING status, you take an image copy or use REPAIR utility.
87) What is CHECK PENDING ?
When a table is LOADed with ENFORCE NO option, then the table is left in CHECK PENDING status. It means that the LOAD utility did not perform constraint checking.
88) What is QUIESCE?
A QUIESCE flushes all DB2 buffers on to the disk. This gives a correct snapshot of the database and should be used before and after any IMAGECOPY to maintain consistency.
89) What is a clustering index ? –
Causes the data rows to be stored in the order specified in the index. A mandatory index defined on a partitioned table space.
90) How many clustering indexes can be defined for a table?
Only one.
91) What is the difference between primary key & unique index ?
Primary : a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table.
92) What is sqlcode -922 ?
Authorization failure
93) What is sqlcode -811?
SELECT statement has resulted in retrieval of more than one row.
94) What does the sqlcode of -818 pertain to? –
This is generated when the consistency tokens in the DBRM and the load module are different.
95) Are views updateable ?
Not all of them. Some views are updateable e.g. single table view with all the fields or mandatory fields. Examples of non-updateable views are views which are joins, views that contain aggregate functions(such as MIN), and views that have GROUP BY clause.
96) If I have a view which is a join of two or more tables, can this view be updateable? –
No.
97) What are the 4 environments which can access DB2 ?
TSO, CICS, IMS and BATCH
98) What is an inner join, and an outer join ?
Inner Join: combine information from two or more tables by comparing all values that meet the search criteria in the designated column or columns of on e table with all the clause in corresponding columns of the other table or tables. This kind of join which involve a match in both columns are called inner joins.
Outer join is one in which you want both matching and non matching rows to be returned. DB2 has no specific operator for outer joins, it can be simulated by combining a join and a correlated sub query with a UNION.
99) What is FREEPAGE and PCTFREE in TABLESPACE creation?
PCTFREE: percentage of each page to be left free
FREEPAGE: Number of pages to be loaded with data between each free page
100) What are simple, segmented and partitioned table spaces ?
Simple Tablespace:
Can contain one or more tables
Rows from multiple tables can be interleaved on a page under the DBAs control and maintenance
Segmented Tablespace:
Can contain one or more tables
Tablespace is divided into segments of 4 to 64 pages in increments of 4 pages. Each segment is dedicated to single table. A table can occupy multiple segments
Partitioned Tablespace:
Can contain one table
Tablespace is divided into parts and each part is put in a separate VSAM dataset.
101) What is filter factor?
one divided by the number of distinct values of a column.
102) What is index cardinality? –
The number of distinct values a column or columns contain.
103) What is a synonym ?
Synonym is an alternate name for a table or view used mainly to hide the leading qualifier of a table or view.. A synonym is accessible only by the creator.
104) What is the difference between SYNONYM and ALIAS?
SYNONYM: is dropped when the table or tablespace is dropped. Synonym is available only to the creator.
ALIAS: is retained even if table or tablespace is dropped. ALIAS can be created even if the table does not exist. It is used mainly in distributed environment to hide the location info from programs. Alias is a global object & is available to all.
105) What do you mean by NOT NULL WITH DEFAULT? When will you use it?
This column cannot have nulls and while insertion, if no value is supplied then it wil have zeroes, spaces or date/time depending on whether it is numeric, character or date/time.
Use it when you do not want to have nulls but at the same time cannot give values all the time you insert this row.
106) What do you mean by NOT NULL? When will you use it?
The column cannot have nulls. Use it for key fields.
107) When would you prefer to use VARCHAR?
When a column which contains long text, e.g. remarks, notes, may have in most cases less than 50% of the maximum length.
108) What are the disadvantages of using VARCHAR?
1. Can lead to high space utilization if most of the values are close to maximum.
2. Positioning of VARCHAR column has to be done carefully as it has performance implications.
3. Relocation of rows to different pages can lead to more I/Os on retrieval.
109) How do I create a table MANAGER ( EMP#, MANAGER) where MANAGER is a foreign key which references to EMP# in the same table? Give the exact DDL.
First CREATE MANAGER table with EMP# as the primary key. Then ALTER it to define the foreign key.
When is the authorization check on DB2 objects done - at BIND time or run time?
At run time.
110) What is auditing?
Recording SQL statements that access a table. Specified at table creation time or through alter.
Saturday, July 09, 2011
Oracle JDBC in general - How do I install the Thin driver?
Oracle JDBC in general - How do I install the Thin driver?
Put the jar files in a convenient location and include the appropriate jar files in your classpath. See What are all these files for? to determine which files you need.
Put the jar files in a convenient location and include the appropriate jar files in your classpath. See What are all these files for? to determine which files you need.
Wednesday, April 27, 2011
HR round interview questions and answers
HR round interview questions and answers
* HR Round/First Round Job Interview
* Tell me something about yourself?
* Why should we hire you?
* What are your greatest strengths?
* What are your greatest weaknesses?
* Why are you looking for a change?
* What do you like/dislike most about your current or last position?
* How do you handle pressure?
* What are your career goals? or Where do you see yourself in 3-5 years?
* How did you handle your most challenging experience in your previous job?
* How will your qualification help you in doing this job?
* What do you know about our organization?
* Why do you wish to join our organization?
* What is your expected salary/CTC?
* How have your strengths helped you in getting your work done?
* Where do you see yourself two years from now?
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 1:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 2:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 3:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 4:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 5:
* Common Inteview Mistakes - Interview the Interviewer
* Interview Questions and Answers
* Common Interview Questions and Their Answers.
* What would you rate as your greatest weaknesses?
* Don’t you think you are overqualified for this job?
* How would you honestly evaluate the strengths and weaknesses of your previous/current company/boss/team?
* Your competitor presses you to reveal some confidential information about your current or previous employer.
* If you came on board with us, what changes would you make in the system?
* I find that you have changed jobs many times so far. Why is it so?
* How many hours a day/a week do you work?
* We would like to hear about your goals.
* Tell me about a situation when your work was criticized
* What are your outside interests ?
* POSSIBLE FOLLOW-UP QUESTION: what would you do if he still did not change his ways?
* May I contact your present employer for a reference ?
* Where could you use some improvement ?
* What do you worry about ?
* How do you feel about working nights and weekends ?
* Are you willing to relocate or travel ?
* Do you have the stomach to fire people? Have you had experience firing many people ?
* Why have you had so many jobs ?
* Would you lie for the company ?
* Looking back, what would you do differently in your life ?
* Could you have done better in your last job ?
* Describer a situation that didn’t suffer because of you but from external conditions beyond your control ?
* Can you work under pressure ?
* What makes you angry ?
* Why aren’t you earning more money at this stage of your career ?
* Who has inspired you in your life and why?
* What was the toughest decision you ever had to make?
* Tell me about the most boring job you have ever had
* What changes would you make if you came on board?
* How many hours a week do you normally work?
* What is the most difficult part of being a (job title)?
* Have you consider starting your own business?
* What are your goals?
* What do you for when you hire people?
* “The Salary Question” – How much money do you want ?
* Illegal questions include any regarding your age…number and ages of your children .....
* What was the toughest part of your last job?
* How do you define success…and how do you measure up to your own definition?
* If you won $10 million lottery, would you still work?
* Looking back on your last position, have you done your best work?
* Why should I hire you from the outside when I could promote someone from within?
* Tell me something negative you’ve heard about our company…
* On a scale of one to ten, rate me as an interviewer.
* What to Ask After the Offer
* What are the boss's strengths and weaknesses?
* How much change is in the works at your prospective company, and what kind?
* How many of my skills and experiences will I be able to use and learn?
* How many people have held the position in the past several years?
* Questions To Ask The HR
* Tips For Interview
* How Effective are HR Round Interview Tips
* What do you find is the most enjoyable part, working in a company?
* What inspired you to come and attend my company’s interview?
* What would be your ideal work atmosphere?
* What do you think is our company’s philosophy?
* How would you overcome your weaknesses?
* If your work demands a lot of your time, much more than the stipulated hours, would you be alright with that?
* HR round Final Standard Interview Questions asked by Human resources people
* List of Questions asked during HR round of an Interview
* Hr Round Questions-IBM
* How To Clear HR Round In IT Companies?
* Investment Banking Interview Questions - HR/Personal Round
* Administrative Assistant Interview Questions - HR/Personal Round
* Microsoft Interview questions in HR or recruiter Round
* HR Round/First Round Job Interview
* Tell me something about yourself?
* Why should we hire you?
* What are your greatest strengths?
* What are your greatest weaknesses?
* Why are you looking for a change?
* What do you like/dislike most about your current or last position?
* How do you handle pressure?
* What are your career goals? or Where do you see yourself in 3-5 years?
* How did you handle your most challenging experience in your previous job?
* How will your qualification help you in doing this job?
* What do you know about our organization?
* Why do you wish to join our organization?
* What is your expected salary/CTC?
* How have your strengths helped you in getting your work done?
* Where do you see yourself two years from now?
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 1:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 2:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 3:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 4:
* Below are the Interview Questions, which were asked in HR Round. No one will GET second chance to impress. Very very Impressive Questions and Answers. Question 5:
* Common Inteview Mistakes - Interview the Interviewer
* Interview Questions and Answers
* Common Interview Questions and Their Answers.
* What would you rate as your greatest weaknesses?
* Don’t you think you are overqualified for this job?
* How would you honestly evaluate the strengths and weaknesses of your previous/current company/boss/team?
* Your competitor presses you to reveal some confidential information about your current or previous employer.
* If you came on board with us, what changes would you make in the system?
* I find that you have changed jobs many times so far. Why is it so?
* How many hours a day/a week do you work?
* We would like to hear about your goals.
* Tell me about a situation when your work was criticized
* What are your outside interests ?
* POSSIBLE FOLLOW-UP QUESTION: what would you do if he still did not change his ways?
* May I contact your present employer for a reference ?
* Where could you use some improvement ?
* What do you worry about ?
* How do you feel about working nights and weekends ?
* Are you willing to relocate or travel ?
* Do you have the stomach to fire people? Have you had experience firing many people ?
* Why have you had so many jobs ?
* Would you lie for the company ?
* Looking back, what would you do differently in your life ?
* Could you have done better in your last job ?
* Describer a situation that didn’t suffer because of you but from external conditions beyond your control ?
* Can you work under pressure ?
* What makes you angry ?
* Why aren’t you earning more money at this stage of your career ?
* Who has inspired you in your life and why?
* What was the toughest decision you ever had to make?
* Tell me about the most boring job you have ever had
* What changes would you make if you came on board?
* How many hours a week do you normally work?
* What is the most difficult part of being a (job title)?
* Have you consider starting your own business?
* What are your goals?
* What do you for when you hire people?
* “The Salary Question” – How much money do you want ?
* Illegal questions include any regarding your age…number and ages of your children .....
* What was the toughest part of your last job?
* How do you define success…and how do you measure up to your own definition?
* If you won $10 million lottery, would you still work?
* Looking back on your last position, have you done your best work?
* Why should I hire you from the outside when I could promote someone from within?
* Tell me something negative you’ve heard about our company…
* On a scale of one to ten, rate me as an interviewer.
* What to Ask After the Offer
* What are the boss's strengths and weaknesses?
* How much change is in the works at your prospective company, and what kind?
* How many of my skills and experiences will I be able to use and learn?
* How many people have held the position in the past several years?
* Questions To Ask The HR
* Tips For Interview
* How Effective are HR Round Interview Tips
* What do you find is the most enjoyable part, working in a company?
* What inspired you to come and attend my company’s interview?
* What would be your ideal work atmosphere?
* What do you think is our company’s philosophy?
* How would you overcome your weaknesses?
* If your work demands a lot of your time, much more than the stipulated hours, would you be alright with that?
* HR round Final Standard Interview Questions asked by Human resources people
* List of Questions asked during HR round of an Interview
* Hr Round Questions-IBM
* How To Clear HR Round In IT Companies?
* Investment Banking Interview Questions - HR/Personal Round
* Administrative Assistant Interview Questions - HR/Personal Round
* Microsoft Interview questions in HR or recruiter Round
Sunday, December 12, 2010
Add the Image Links to the Database Results
Add the Image Links to the Database Results
1. Locate the database column value named <>, and then delete it.
2. In the table cell where you just removed the column value, insert the City.gif file from your Web.
3. Right-click the image, and then click Picture Properties on the shortcut menu.
4. Click the General tab, and then click Browse.
5. Click Parameters.
6. In the path field, remove the current path. Click Insert Field Parameter, and then click FavoriteImage.
7. Click OK three times.
You will see a small broken image icon in the table column.
8. Save the page, and then click the Preview in Browser button on the Standard toolbar.
Tuesday, August 17, 2010
Sybase Interview Questions and Answers
Sybase Interview Questions and Answers
* Explain about the Sybase group?
* Explain What is Update Statistics in Sybase ?
* Explain about Sybase 365?
* State some of the products of Sybase?
* Explain about the features of Sybase IQ?
* State some of the criticism about Sybase IQ?
* Explain the structure of Adaptive server enterprise?
* What is the difference in storage type of numeric and decimal data types in sybase ?
* Explain about the Data integration suite features?
* Explain about Power Designer Data modeling software?
* Explain about the mainframe connect tools from Sybase?
* Explain the benefits you can get from Mainframe connect?
* What is a Coalesce? What is the equivalent of Oracle/Db2 Coalesce Function in Sybase ?
* Explanation about replication server software?
* Explain about Open switch business continuity software?
* Explain about Mirror Activator Disk mirroring?
* What is procedure cache and data cache in Sybase?
* Give the benefits of Data integration suite?
* Explain about Enterprise scalability and ROI of Data integration suite?
* What are the vital features of Sybase?
* Explain about ETL data integration software?
* Explain about Mobile enterprise application enablement?
* What is SQL Server and ASE?
* How to start/stop ASE when CPU reboots ?
* What is the command for quitting from Sybase?
* How do I move tempdb off of the Master Device?
* How do I correct timeslice -201
* What is RAID and Sybase?
* What is the relationship between JDBC and Sybase?
* How to swap a db device with another
* Server naming and renaming
* How to clear tempdb when the tempdb gets filled in Sybase?
* How do I interpret the tli strings in the interface file?
* How can I tell the datetime my Server started?
* Raw partitions or regular files?
* How can you change to get the decimal separator as comma instead of the decimal point (.)?
* How Can I Run the ASE Upgrade Manually?
* We have lost the sa password, what can we do?
* What is Open Server in Sybase?
* How do I set a password to be null?
* Does Sybase support Row Level Locking?
* How To Change varchar(m) to varchar(n) in Sybase?
* Given a table which contains some rows with duplicate keys, how would you remove the duplicates?
* What Is Table Partitioning in Sybase ?
* Can I Partition Any Table in Sybase ?
* How Do I Choose Which Tables To Partition in Sybase?
* Does Table Partitioning Require User-Defined Segments in Sybase?
* How to view the log files in sybase
* Can I Run Any Transact-SQL Command on a Partitioned Table in Sybase ?
* How Does Partition Assignment Relate to Transactions in Sybase?
* Can Two Tasks Be Assigned to the Same Partition in Sybase?
* Must I Use Multiple Devices to Take Advantage of Partitions in Sybase?
* How Do I Create A Partitioned Table That Spans Multiple Devices in Sybase?
* How Do I Take Advantage of Table Partitioning with bcp in Sybase ?
* How to manually drop a table in Sybase
* Why not max out all my columns Sybase?
* What's a good example of a transaction? Sybase
* What's a natural key?in Sybase
* How to Save space when inserting rows monotonically ?
* How to compute database fragmentation in Sybase ?
* Tasks a DBA should do in Sybase ...
* How to implement database security ?
* How to Shrink a Database
* How do I audit the SQL sent to the server?
* How to clear a log suspend
* What is the best value for cschedspins?
* What is Trace Flag Definitions in Sybase
* What is Trace Flags -- 5101 and 5102 in Sybase ?
* What is cmaxpktsz good for in Sybase?
* Buildmaster Configuration Definitions in Sybase
* What is CIS and how can I use it?
* If the master device is full, how do I make the master database bigger?
* How do I run multiple versions of Sybase on the same server?
* How do I capture a process's SQL in Sybase?
* How do I turn off marked suspect on my database in Sybase?
* On startup, the transaction log of a database has filled and recovery has suspended, what can I do?
* Why do my page locks not get escalated to a table lock after 200 locks?
* Sybase ASE Performance and Tuning
* Temp Tables and OLTP in Sybase
* Differences between clustered and non-clustered in Sybase ?
* Optimistic versus Pessimistic locking in Sybase?
* How do I force an index to be used in Sybase ?
* Why place tempdb and log on low numbered devices?
* Should I run 32 or 64 bit ASE with Solaris?
* What is Intimate Shared Memory or ISM?
* How do I set TS Role in order to run certain DBCCs...?
* Fixing a Munged Log in Sybase ?
* Hiding your password to isql in Sybase
* How to remove row affected and dashes
* How do I pipe the output of one isql to another?
* Are there any alternatives to isql in Sybase ?
* How do I make isql secure in Sybase?
* How do I pipe the output of isql to a file in Sybase?
* How do I bcp null dates in Sybase?
* Can I use a named pipe to bcp/dump data out or in in Sybase?
* How do I exclude a column in Sybase ?
* Alternative to row at a time processing in Sybase ?
* When should I execute an sp_recompile in Sybase?
* What are the different types of (All Page) locks in Sybase?
* What's the purpose of using holdlock in Sybase?
* How do I find the oldest open transaction in Sybase?
* How do I check if log truncation is blocked in Sybase?
* The timestamp datatype in Sybase ?
* When are stored procedures compiled in Sybase ?
* What causes re-resolution of a stored procedure in Sybase?
* What will cause the size of a stored procedure to grow in Sybase?
* How do I manipulate varbinary columns in Sybase ?
* How do I remove duplicate rows from a table in Sybase?
* How to emulate the Oracle decode function/crosstab in Sybase
* How to implement if-then-else in a select clause in Sybase
* How to pad with leading zeros an int or smallint in Sybase ?
* Divide by zero and nulls in Sybase
* Convert months to financial months in Sybase
* Hierarchy traversal - BOMs in Sybase
* Calling OS commands from a trigger or a stored procedure in Sybase
* Advantages/Features of Using Identities in Sybase
* Disadvantages/Drawbacks of Using Identities in Sybase
* Is the Identity the equivalent of Oracles auto-sequencing in Sybase?
* How do I configure Identities in Sybase?
* How do I Configure the burn factor in Sybase?
* How do I tell which tables have identities in Sybase ?
* What is my identity burn factor vulnerability right now in Sybase?
* Optimizing your Identity setup for performance and maintenance in Sybase
* Recovery from Large Identity value gaps in Sybase
* How do I generate Sequential Keys w/o the Identity feature in Sybase?
* Optimizing your home grown Sequential key generating process for any version of Sybase
* How can I execute dynamic SQL with ASE in Sybase?
* Is it possible to concatenate all the values from a column and return a single row?
* Selecting rows N to M without Oracles rownum in Sybase?
* How can I return number of rows that are returned from a grouped query without using a temporary table?
* How to feed the result set of one stored procedure into another in Sybase ?
* Is it possible to do dynamic SQL before ASE 12 in Sybase?
* What is Open Client in Sybase?
* What is the difference between DB-lib and CT-lib in Sybase?
* What is this TDS protocol in Sybase?
* I have upgraded to MS SQL Server 7.0 and can no longer connect from Sybase's isql.
* The Basics of Connecting to Sybase
* Connecting to ASE Using OLTP in Sybase
* Which version of Open Client works with which ASE in Sybase?
* How do I tell the version of Open Client I am running in Sybase?
* What is ASA in Sybase?
* On what platforms is ASA supported?
* What applications is ASA good for?
* Does ASA Support Replication in Sybase?
* What is ASA UltraLite in Sybase?
* What is Replication Server in Sybase?
* Replication Server Components in Sybase?
* What is the Difference Between Replication Server and SQL Remote in Sybase?
* How can I improve throughput in Sybase?
* Where should I install replication server in Sybase
* Using large raw partitions with Replication Server on Unix in Sybase
* How to replicate col = col + 1 in Sybase ?
* What is the difference between an LTM and a RepAgent in Sybase?
* Which should I use, RepAgent or LTM in Sybase?
* Why am I running out of locks on the replicate side in Sybase ?
* Someone was playing with replication and now the transaction log on OLTP is filling
ANSWERS
Saturday, March 06, 2010
10 Best and Worst Jobs for 2010
10 Best and Worst Jobs for 2010
Here are the 10 best jobs of 2010
1. Actuary
2. Software Engineer
3. Computer Systems Analyst
4. Biologist
5. Historian
6. Mathematician
7. Paralegal Assistant
8. Statistician
9. Accountant
10. Dental Hygienist
Here are the 10 worst jobs of 2010
1. Roustabout
2. Lumberjack
3. Ironworker
4. Dairy Farmer
5. Welder
6. Garbage Collector
7. Taxi Driver
8. Construction Worker
9. Meter Reader
10. Mail Carrier
Monday, October 19, 2009
DBA FAQ
This topic has been covered in several Oracle technical bulletins
and a few IOUG papers, so I'll present it very briefly. Any
transaction's rollback area can be measured by monitoring the
changes in the system statistics tables during its run. This means
that a valid reading requires that nothing else be running during the
time the test is taking place.
All you have to do is store the result of the following query
immediately before and after running your test:
SELECT SUM(WRITES) FROM V$ROLLSTAT;
When the transaction has completed, and you have the beginning
and ending values, the size of the rollback information generated
can be calculated:
ENDING_WRITES - BEGINNING_WRITES - 54 = ROLLBACK INFO GENERATED.
NOTE: The "54" is the rollback overhead that corresponds to the
amount of overhead required by a table insert operation. This assumes
that you're storing these values in tables. If you're just tracking
them on paper, then ignore this factor.
This will tell you how much rollback space you need to handle this
transaction; knowing how many transactions will be running at once
will give you an idea of how much space will be needed in your
ROLLBACKS tablespace.
Dropping Public Rollback Segments
and a few IOUG papers, so I'll present it very briefly. Any
transaction's rollback area can be measured by monitoring the
changes in the system statistics tables during its run. This means
that a valid reading requires that nothing else be running during the
time the test is taking place.
All you have to do is store the result of the following query
immediately before and after running your test:
SELECT SUM(WRITES) FROM V$ROLLSTAT;
When the transaction has completed, and you have the beginning
and ending values, the size of the rollback information generated
can be calculated:
ENDING_WRITES - BEGINNING_WRITES - 54 = ROLLBACK INFO GENERATED.
NOTE: The "54" is the rollback overhead that corresponds to the
amount of overhead required by a table insert operation. This assumes
that you're storing these values in tables. If you're just tracking
them on paper, then ignore this factor.
This will tell you how much rollback space you need to handle this
transaction; knowing how many transactions will be running at once
will give you an idea of how much space will be needed in your
ROLLBACKS tablespace.
Dropping Public Rollback Segments
Tuesday, June 09, 2009
Accessing partition table
Accessing partition table-
Select * from aa partion(pa1);
Drop partion
-Alter table AA
drop partion pa1;
SQL Language Extension-
Oracle * provide new built-in datatype, object datatypes, nested tables, and a no of other features that require new DDL extension.
VARRAY
REF
LOBS
Create table AA(a N (10)
B date,
C varchar2 (10));
Create type aa1 as varray (5) of number (5);
The UTLBSTAT and UTLESTAT script to get general overview of database 's performance over a certain period of time.
UTLBSTAT creates table and views containing cumulative database performance summary information at the time when the script runs .All the objects create by UTLBSTAT contain word login.
Utlbstat.sql
UTLESTAT creates table and views containing cumulative database performance summary information at the time when the script runs .All the objects create by UTLESTAT contain word end.
UTLESTAT spools the results of these SQL statements to a file called REPORT.TXT
Utlestat.sql
Determine the shared Pool Performance.
The shared pool is one of the memory structures in SGA .It is comprised of the data dictionary and the library cache. Check v$sgastat
The data dictionary cache buffers data dictionary objects that contain data about tables, indexes, users and all other objects.
The Library Cache/SQL Cache buffers previously executed queries, so that they need not be reloaded and reparsed if user calls them again.
Otherwise if the information is not in the buffer then oracle must get it from disk.
The V$LIBRAY CACHE View stores performance data for library cache and V$ROWCACHE view stores performance data for the data dictionary cache.
Sometime we may have to increase the value of initialization parameter SHARED_POOL_SIZE.
To improve the performance .
Redo Log --
Oracle 8 stores all changes to the database, even uncommitted changes, in the redo log files.
LGWR writes .
Alter database archievelog
Edit the parameter initialization file.
Log_archieve_start =true -turn it on
Log_archieve_dest=c:/oracle/ora81/archieve -location
log_archieve_format="ARCH%S.LOG" - name format for archieve file .
%S for log sequence number .
By querying the V$SESSION view , we can determine who is logged on ,as well as information such as the time of logon .
Kill a session - ALTER system kill session '&sid,&serial'
Select Sid,serial#,status from V$session where username='name';
Unbalanced Index ?
if we do have lot on index on a table and we are doing I/U/D frequently then there is a problem of disk contention . To check this problem sees the BLEVEL value in DBA_INDEXES and if it is 1,2,3,4 then it?s ok else rebuild the index .
Alter index satish.a_satish rebuild unrecoverable ;
Comments on table and columns
Select * from aa partion(pa1);
Drop partion
-Alter table AA
drop partion pa1;
SQL Language Extension-
Oracle * provide new built-in datatype, object datatypes, nested tables, and a no of other features that require new DDL extension.
VARRAY
REF
LOBS
Create table AA(a N (10)
B date,
C varchar2 (10));
Create type aa1 as varray (5) of number (5);
The UTLBSTAT and UTLESTAT script to get general overview of database 's performance over a certain period of time.
UTLBSTAT creates table and views containing cumulative database performance summary information at the time when the script runs .All the objects create by UTLBSTAT contain word login.
Utlbstat.sql
UTLESTAT creates table and views containing cumulative database performance summary information at the time when the script runs .All the objects create by UTLESTAT contain word end.
UTLESTAT spools the results of these SQL statements to a file called REPORT.TXT
Utlestat.sql
Determine the shared Pool Performance.
The shared pool is one of the memory structures in SGA .It is comprised of the data dictionary and the library cache. Check v$sgastat
The data dictionary cache buffers data dictionary objects that contain data about tables, indexes, users and all other objects.
The Library Cache/SQL Cache buffers previously executed queries, so that they need not be reloaded and reparsed if user calls them again.
Otherwise if the information is not in the buffer then oracle must get it from disk.
The V$LIBRAY CACHE View stores performance data for library cache and V$ROWCACHE view stores performance data for the data dictionary cache.
Sometime we may have to increase the value of initialization parameter SHARED_POOL_SIZE.
To improve the performance .
Redo Log --
Oracle 8 stores all changes to the database, even uncommitted changes, in the redo log files.
LGWR writes .
Alter database archievelog
Edit the parameter initialization file.
Log_archieve_start =true -turn it on
Log_archieve_dest=c:/oracle/ora81/archieve -location
log_archieve_format="ARCH%S.LOG" - name format for archieve file .
%S for log sequence number .
By querying the V$SESSION view , we can determine who is logged on ,as well as information such as the time of logon .
Kill a session - ALTER system kill session '&sid,&serial'
Select Sid,serial#,status from V$session where username='name';
Unbalanced Index ?
if we do have lot on index on a table and we are doing I/U/D frequently then there is a problem of disk contention . To check this problem sees the BLEVEL value in DBA_INDEXES and if it is 1,2,3,4 then it?s ok else rebuild the index .
Alter index satish.a_satish rebuild unrecoverable ;
Comments on table and columns
Wednesday, April 01, 2009
Tuesday, January 13, 2009
WHAT EXACTLY IS A DBA?
WHAT EXACTLY IS A DBA?
The position of Database Administrator -- DBA for short -- means many things to many people. In a small development shop the duties are much broader than in a highly stratified major corporation. Whether a company is doing development or adopting a third part package will also determine the needs of the DBA position. Knowing what is expected of the position and knowing how the position envisioned fits within the company hierarchy is critical. In “ORACLE 8.0 Administration and Management” I list the following as a list of DBA job functions:
1. Installing and upgrading the ORACLE Server and application tools.
2. Allocating system storage and planning future storage requirements for the database.
3. Creating primary database storage structures (tablespaces) once developers have
designed an application.
4. Creating primary database objects (tables, views, indexes) once application
developers have designed an application.
5. Modifying the database structure, as necessary, from information given by application
developers.
6. Enrolling users and maintaining system security.
7. Ensuring compliance with Oracle License agreements.
8. Controlling and monitoring user access to the database.
9. Monitoring and optimizing the performance of the database.
10. Planning for backup and recovery of database information.
11. Maintaining archived data on appropriate storage devices.
12. Backing and restoring the database.
13. Contacting Oracle Corporation for technical support.
So let’s see if we can distill this down into some general categories of knowledge:
* Installation
* Configuration management
* Security
* Monitoring and Tuning
* Backup and Recovery
* Trouble Shooting
* Vendor Interface
So to be a full-charge DBA a candidate must be knowledgeable in all of the above areas.
The position of Database Administrator -- DBA for short -- means many things to many people. In a small development shop the duties are much broader than in a highly stratified major corporation. Whether a company is doing development or adopting a third part package will also determine the needs of the DBA position. Knowing what is expected of the position and knowing how the position envisioned fits within the company hierarchy is critical. In “ORACLE 8.0 Administration and Management” I list the following as a list of DBA job functions:
1. Installing and upgrading the ORACLE Server and application tools.
2. Allocating system storage and planning future storage requirements for the database.
3. Creating primary database storage structures (tablespaces) once developers have
designed an application.
4. Creating primary database objects (tables, views, indexes) once application
developers have designed an application.
5. Modifying the database structure, as necessary, from information given by application
developers.
6. Enrolling users and maintaining system security.
7. Ensuring compliance with Oracle License agreements.
8. Controlling and monitoring user access to the database.
9. Monitoring and optimizing the performance of the database.
10. Planning for backup and recovery of database information.
11. Maintaining archived data on appropriate storage devices.
12. Backing and restoring the database.
13. Contacting Oracle Corporation for technical support.
So let’s see if we can distill this down into some general categories of knowledge:
* Installation
* Configuration management
* Security
* Monitoring and Tuning
* Backup and Recovery
* Trouble Shooting
* Vendor Interface
So to be a full-charge DBA a candidate must be knowledgeable in all of the above areas.
Monday, November 03, 2008
Database Administrator (DBA) Articles
Database Administrator (DBA) Articles
Why This SQL Server DBA is Learning Powershell |
In this article, I will describe several examples of using PowerShell that I would hope a DBA would find useful. My scripts will demonstrate how to run SQL queries, WMI queries or SMO code on one or more machines, and help you to better manage multiple database servers. All of the scripts have been tested on SQL Server 2005. . Read more... By Ron Dameron |
MySQL_Database_Administration |
If you need to administer MySQL, this article gets you off to a good start. The first of a multi-part series, it is excerpted from chapter four of the book MySQL Administrator's Guide, written by Paul Dubois . Read more... By Sams Publishing |
Manually Creating an Oracle Database on Windows |
Manually Creating an Oracle Database on Windows Below are the steps involved in manual database creation on Windows. . Read more... By john niveth |
How to Develop, Maintain, and Support a Quality Management and Development Process |
The task of defining test plans, acceptance criteria, and testing deliverables and processes for any software development effort can face many different and evolving challenges, from identifying applicable processes to maintaining those decisions over time. . Read more... By James Downs |
An Introduction to Linux Shell Scripting for DBAs |
About seven years ago, Oracle released the first commercial database on Linux. Since then, Oracle, Red Hat, and Novell/SUSE have been steadily collaborating on changes to Linux kernel as they relate to database and application performance. . Read more... By Casimir Saternos |
Tuning Up for OLTP and Data Warehousing - Part 3 |
There are many types of DBAs. Some DBAs work in the developer arena, while others are heavy into performance and tuning, and still other DBAs fall into the operational aspects of managing SQL Server. . Read more... By Gregory A. Larsen |
Tuning Up for OLTP and Data Warehousing - Part 3 |
We mentioned that 20 to 25 percent of performance tuning improvements result from configuring the database manager, database, and tablespace container and parameter settings. But 75 percent or more of performance improvements come from properly tuning SQL. . Read more... By Scott Hayes and Philip Gunning |
Oracle Workshop's Support for Java EE 5 Web Standards |
For a long time, J2EE seemed a powerful, complex technology. If you took the time to fully understand it, however, you would have discovered ingenious solutions for building scalable component-based multi-tier enterprise applications. . Read more... By Andrei Cioroianu |
MySQL Tuning: Getting the most out of your database |
This article will deal with a few basic MySQL Tuning options that can make queries run faster on your MySQL database. This problem can be approached from several different angles. . Read more... By |
A Quick Look at MySQL 6.0’s New Backup |
I still remember the day. I was working for a large systems integrator on a very major account, and had responsibility for some DB2 databases, but also had the unfortunate duty of also taking care of some legacy IMS databases!' . Read more... By Robin Schumacher |
What use is a Development DBA? |
I'm sure that there are many Developers who would respond to that question immediately, with something like: 'None, other than to obstruct me at every opportunity!' 'Well, he'd be more use if he stopped breaking things!' . Read more... By Doug Burns |
Which Scripting Language for Sybase Administration on Windows? |
This paper considers five scripting options available to automate the administration of Sybase database servers on Windows. . Read more... By Caroline Walsh |
DBA: TEN YEARS AFTER AND BEYOND |
In March of 1990, a little booklet of ancient and medieval rules appeared on the market. This had the strange name of De Bellis Antiquitatis (and known ever since as just DBA). . Read more... By Bob Beattie |
Certifications Compared: Oracle vs. DB2 vs. SQL Server |
If you’re looking into DBA certification, you’ve got to decide with which product to certify. Which DBA certification is most marketable? Which best fits you? How do the vendors’ certification requirements vary, and what are the costs and the time involved? . Read more... By Howard Fosdick |
Basic Java Persistence API Best Practices |
Consider and employ these simple approaches to make your Java Persistence API applications more maintainable. . Read more... By Dustin Marx |
How to find out virtual index from database? |
Virtual index can be created in oracle database which doesn't has any physical body and location. It can create with NOSEGMENT clause for testing purpose. . Read more... By Gitesh Trivedi |
SQL Server Performance Coding Standards |
In this article Amol Ramesh Kulkarni provides a list of his top SQL Server Performance Coding Standards . Read more... By Amol Kulkarni |
Getting started with Bazaar for MySQL code |
Since you're reading this, you probably know that Sun is switching to the Bazaar version control system for all development work on the MySQL server. Unlike the version control system that we've been using previously, . Read more... By Amol Kulkarni |
The SQL Builder Development Accelerators |
DB2 9.5 and IBM Data Studio: Part 8: The SQL Builder Development Accelerators – The Rest of the Story . Read more... By Paul Zikopoulos |
Using Database Advisors |
Advisors are powerful tools that provide specific advice on how to address key database management challenges, covering a wide range of areas, including space, performance, and undo management. . Read more... By Sushma Jagannath |
Introduction to SQL 2005 Profiler Part 1 |
Profiler is a tool that monitors the events and activity running on a SQL Server. Using profiler, this monitoring can be viewed, saved, and replayed. This article focuses on using Profiler with SQL Server 2005, but the tool is also included with SQL Server 2000 and SQL Server 2008. Read more... By Don Schlichting |
Automate Audit Requests |
In this article TJay Belt describes a process to help respond to audit requests in a timely manner. Read more... By TJay Belt |
MySQL Workbench for Database Change Management |
Managing database change is an incredibly important discipline that very few database professionals overtly talk or worry about until they're in the thick of things with a particular database - moving it from development to production, making changes to a newly installed production database, or implementing an updated version of the database (new tables, modifications to existing objects, etc.) in a SaaS application. It's at that point where change management becomes very important because if you don't do things right the first time, you can make a royal mess of things and even (in a small number of cases) reach the point of no return where you've completely torched your database. Read more... By Robin Schumacher |
Posting Microsoft Access Information “Into the clouds |
Part one of this article demonstrated how to retrieve data and save it into XML using Microsoft Access and MSXML. Part 2 shows how to add new data to a Web2 website ("in the clouds"). Read more... By Garry Robinson |
Accelerating Data Warehouses |
An option of Oracle Database 11g Enterprise Edition, Oracle OLAP 11g is a full-featured online analytical processing engine. Because Oracle OLAP 11g is embedded in Oracle Database, it benefits from database scalability, security, and manageability features. Read more... By Dan Vlamis |
ERP and Data Migration to packages like SAP, PeopleSoft |
ERP and Data Migration to packages like SAP, PeopleSoft Read more... By |
A look at Falcon Diagnostic Tables |
Performance tuning is one of the top disciplines (if not THE top discipline) that database professionals want to excel at. Being able to take a system that's running sluggish and turn it into one that's running as fast as a scalded dog is a talent that's part art and part science, but whatever the combination necessary to make it happen, there will always be strong demand for folks who are good at it. Read more... By Robin Schumacher |
SQL Server Management Studio Reports and Dashboard |
SQL Server 2005 and SQL Server 2008 provide graphical reports for monitoring system health and performance. While there have always been various queries, stored procedures, and of late, Dynamic Management Views, to gather system statistics, none were graphical. . Read more... By Don Schlichting |
Authorizing Access to Dynamic Spatial-Temporal Data |
Authorizing access to individual data objects based on spatial and temporal references is a complex task. Read this case study to learn one feasible approach. Read more... By Lucas Jellema |
Build a Google Talk Client Using Oracle ADF Faces Rich Client and the Active Data Service |
As Oracle OpenWorld 2007 made very clear, the integration of Web 2.0 concepts and trends into enterprise applications is a major trend in application development. Oracle Fusion Applications offer a good example of how combining very appealing, visually rich user interfaces with popular internet trends such as social bookmarking and instant messaging (IM) lead to attractive and productive applications.... Read more... By Lucas Jellema |
How the MySQL Enterprise Upgrade Advisor Helps DBAs Avoid Being Bitten by Known Bugs |
In an earlier article I described how MySQL Enterprise takes the guesswork out of deciding which version of the MySQL server customers should be running by providing alerts around regularly scheduled Monthly Rapid Update and Quarterly Service Pack releases of the Enterprise Server. Read more... By Budi Raharjo |
The Basic Steps to Connect Oracle and Java Program |
Traditionally, up to Oracle8 Release 8.0.5 the management of free and used extents of a tablespace was done in the data dictionary. These “traditional” tablespaces are also called “Dictionary Managed Tablespaces”, in order to differentiate them from a new type of table space called Locally Managed Tablespaces introduced in Oracle8i Release 8.1.5.... Read more... By Budi Raharjo |
Locally managed tablespaces in Oracle |
Traditionally, up to Oracle8 Release 8.0.5 the management of free and used extents of a tablespace was done in the data dictionary. These “traditional” tablespaces are also called “Dictionary Managed Tablespaces”, in order to differentiate them from a new type of table space called Locally Managed Tablespaces introduced in Oracle8i Release 8.1.5.... Read more... By Manikandan Govindaraj |
Managing Complex XML Data in Oracle XML DB 11g |
Learn how to manage complex XML with Oracle XML DB 11g, including how to change schema online... Read more... By V.J. Jain |
SQL Server DBA : Adding users in SQL Server |
SQL Server provides an effective method for adding users in SQL Server and for managing data and information so that it can easily be stored and retrieved from the underlying files in order to provide the functionality it is designed for ... Read more... By |
The DB2 for Linux, UNIX, and Windows DBA Checklist |
While databases are becoming more and more self-aware and self-healing, they still require some monitoring to keep them running as efficiently as possible. Just like your car, a database requires some checks to keep it running optimally. Read more... By Dwaine Snow |
SQL Server DBA Dashboard |
This article examines a tool called the "SQL Server DBA Dashboard" that provides a number of different Custom Reports that can be used to monitor activities within a SQL Server instance. Read more... By Gregory A. Larsen |
MySQL for Oracle DBAs and Developers |
Outline- „X DBA Tips, Tricks, Gotcha's & Tools „X Key Differences for Developers „X Migrating from Oracle to MySQL „X Questions & Answers Read more... By Ronald Bradford |
Instance Shared Memory and Semaphore Segments |
This article was written for educational purpose only. Please refer to the related vendor documentation for detail. Read more... By Vinod Sadanandan |
The Self-Taught DBA |
You can’t go to college to become a DBA. Sure, you can take some basic classes on database theory and design, and maybe even a couple classes on specific databases, but there is no comprehensive college program you can take to become a DBA. Read more... By Brad McGehee |
Installing Oracle9i Release 2 on Linux |
This article is a comprehensive guide for installing Oracle9i Release 2 (9.2.0.4.0) on the Red Hat Linux Fedora Core 2 operating environment. Read more... By Jeff Hunter |
MySQL 5.1 partitions in practice |
This article explains how to test the performance of a large database with MySQL 5.1, showing the advantages of using partitions. Read more... By Giuseppe Maxia |
Importing Poorly Formatted Text Files using SSIS |
Handling text files from SQL Server Integration Service (SSIS) is not new and I am not going to discuss about importing well formatted text files. There are many occasions when database developers must import text files which are not properly formatted. I will discuss three methods of doing this. For these situations we are going to use Script Component data flow task. Read more... By Dinesh Asanka |
Multiple Selection Through Bitmasks |
Ever wish you could store multiple selections to a single table column? The solution, Bitmask Fields, have been in use for decades. Follow along as Danny Lesandrini shows you how to unlock the power of two. Read more... By Danny Lesandrini |
Integrating Oracle Business Intelligence Enterprise Edition Plus with SOA |
A detailed look at the integration possibilities between Oracle SOA Suite and Oracle Business Intelligence Enterprise Edition Plus, from Oracle ACE Director Mark Rittman. Read more... By Mark Rittman and Joel Crisp |
Migrating Access Apps to SQL Server |
This installment concludes the series started by Marc Israel, Migrating Access Applications to SQL Server by Marc Israel. In previous articles, we discussed some of the migration issues, from upsizing tables to conversion of Access queries to SQL Server stored procs. I've procrastinated on this last topic, Query Optimization, because it's the most difficult to describe. Read more... By Jon Stephens |
Using XML in MySQL 5.1 and 6.0 |
In this article, we discuss the XML functionality available in MySQL, with an emphasis on new features coming online in MySQL 5.1 and MySQL 6.0. We assume that you already have a working knowledge of XML, and that you know what the terms Read more... By Jon Stephens |
Open Source PostgreSQL Developer Bruce Momjian Spills The DB Beans |
The database architect talks about the emergence of a commercial company, EnterpriseDB, behind PostgreSQL and the vitality of the database itself. Read more... By Charles Babcock |
Open Source PostgreSQL Developer Bruce Momjian Spills The DB Beans |
The database architect talks about the emergence of a commercial company, EnterpriseDB, behind PostgreSQL and the vitality of the database itself. Read more... By Charles Babcock |
DB2 9.5 and IBM Data Studio: Using OLE DB to Integrate Data |
So far, in this series about the IBM Data Studio integrated development environment (IDE) that’s available with DB2 Version 9.5 (DB2 9.5), I’ve shown you how to set up database connection objects and the actions that you can perform on them. In addition, Read more... By Paul Zikopoulos |
Installing Oracle Database 11g Release 1 on Oracle Enterprise Linux 5 (32- and 64-bit) |
Learn the basics of installing Oracle Database 11g Release 1 on Oracle Enterprise Linux 5 from the bare metal up (for evaluation purposes only). Read more... By John Smiley |
Oracle RAC Wait Events |
The main difference to keep in mind when monitoring a RAC database versus a single-instance database, is the buffer cache and its operation. In a RAC environment the buffer cache is global across all instances in the cluster and hence the processing differs. Read more... By |
Developing MySQL Applications with Eclipse_CDT |
In September, the Developer Zone featured Chapter 6 of Paul DuBois' MySQL, 3rd edition on Writing C Programs with the MySQL C API. This month, we continue in this series on developing MySQL applications in C with a tutorial from Mark Schoonover about using the Eclipse CDT (C Development Toolkit) as an IDE for developing C applications for MySQL. Read more... By Mark Schoonover |
DB2 9.5 and IBM Data Studio |
At the IBM Information Management Information on Demand (IOD) conference in Las Vegas in October 2007, IBM made a number of major announcements, which included the christening of the DB2 Viper 2 beta as DB2 Version 9.5 (DB2 ... Read more... By Paul Zikopoulos |
Installing SQL Server 2008 |
This article will highlight the steps involved to install SQL Server 2008. The installation is simple and straightforward. Trial and preview versions can be downloaded from Microsoft at ... Read more... By Don Schlichting |
Using Python with TurboGears |
TurboGears offers Python-istas an excellent framework for creating Web-enabled applications backed by an Oracle database. Read more... By Daniel Rubio |
Oracle DBA Exam ( the Oracle Architecture ) |
The Oracle Architecture The Diagram below gives a clear idea of the background processes, memory structures, and disk resources that comprise the Oracle instance, and also of the methods in which they act together to allow users to access information. Read more... By |
Basic Database Design |
Database design is becoming key to developing applications. Almost all web applications are driven by a database, and with Core Data, Cocoa applications are starting to have true database back ends. Therefore it is surprising that so many programmers don’t know anything about database design. So here is a simple overview of the theory behind database design. Read more... By Pilky |
Why DBAs Must Be Jacks-of-All-Trades |
Data is at the center of today's applications; today's organizations simply cannot operate without data. In many ways, business today is data. Without data, businesses would not have the ability to manage finances, conduct transactions, or contact their customers. Databases are created to store and organize this data. The better the design and utility of the database, the better the organization will be positioned to compete for business. Read more... By Craig Mullins |
Locally Managed Indexes |
OK, I'll say it. Oracle does not always work the way I want it to work. The most obvious example of this is how indexes are managed. As data is manipulated, it is evident that the index does not reuse space that it had. For example, if I have a column containing the values A,D,B,E,C,F, and I put an index on this, then the index is created in the following order: Read more... By John Weeg |
Oracle Blocksize and Index Tree Structures |
Each data block within the Oracle index serves as a “node” in the index tree, with the bottom nodes (leaf blocks) containing pairs of symbolic keys and ROWID values. To properly manage the blocks, Oracle controls the allocation of pointers within each data block. As an Oracle tree grows Read more... By Donald K. Burleson |
Monitoring Index Usage in Oracle9i |
DBAs and developers love indexes. They speed up query searches, especially in a data warehouse environment, where the database receives many ad-hoc requests. To avoid fulltable scans, we tend to put indexes on every potentially searchable column. Read more... By Daniel T. Liu |
Automated Table/Index Reorganization In Oracle8i |
Automation can free the DBA of boring, time-consuming tasks and allows him to focus on more challenging activities. Read more... By Mike Hordila |
Learn how to use the various partitioning methods in Oracle9i Release 2. |
Oracle DBAs face an ever growing and demanding work environment. The only thing that may outpace the demands of the work place is the size of the databases themselves. Read more... By Liza Fernandez |
An introduction to foreign keys and referential integrity in MySQL. |
Referential integrity is an important concept in database design. The term refers to a state when all the references in a database are valid and no invalid links exist between the various tables that make up the system. Read more... By Contributor Mellonfire |
An Oracle Instructor's Guide to DBA Tips and Tricks |
This series of articles is a little different than others you may read. It doesn't focus on one, single topic, but it does provide a wealth of interesting information on a lot of different areas. Read more... By Christopher Foot |
Work in multiple databases using these methods |
SQL Server developers sometimes have to use tables residing in a database other than a project's "home" database. This need typically arises when you need to draw information from some other application; Read more... By Arthur Fuller |
Transaction Log Guidelines |
Every SQL Server database has at least two files associated with it: one data file that houses the actual data and one transaction log file. Read more... By Craig S. Mullins |
Understand the ambiguities of compound JOINs in SQL |
This article begins with a test. Look at the SQL below and determine, without using your computer, what the result set will look like. Read more... By Arthur Fuller |
Project Raptor – Oracle's New Tool for DBAs and Developers |
It may be possible that raptors once feasted on toads, and if that were the case, it would be safe to assume that Oracle hopes its new Raptor product will do the same to the Toads of today. Read more... By Steve Callan |
Database Migration - A Planned Approach |
A fairly common event in a database's lifecycle is that of the migration from version "older" to version "newer." Migrating from one version to another may be as simple as exporting the old and importing into the new, but chances are there is a lot more involved than first meets the eye. Read more... By Steve Callan |
Copying Databases from Server to Server |
Method 1-- The fastest way to achieve this is by detaching the database from source server and then attaching the data and the log files to the destination server. Read more... By Rahul Sharma |
Project Raptor - Oracle's New Tool for DBAs and Developers |
It may be possible that raptors once feasted on toads, and if that were the case, it would be safe to assume that Oracle hopes its new Raptor product will do the same to the Toads of today Read more... By Steve Callan |
CASE STUDY OF RMAN IMPLEMENTATION --- Administering the database |
This paper focuses on the real-world implementation of RMAN at Eaton Cutler-Hammer. It includes a brief explanation of various Oracle backup methods, requirements at Eaton Cutler-Hammer Read more... By Ketan Shah, Eaton Cutler-Hammer |
New and Improved Methods for Administering Your Database |
Expose you to some of the database features available in 10g and compare them to the lengthy workarounds that were used in previous Oracle versions. Read more... By Howard Horowitz |
Review of Pro .Net Oracle Programming |
The reason I got this book is simple. I have spent a very large part of my development career firmly in the Microsoft stable. I know how to use Microsoft technolgies such as .net and I am very familiar with Read more... By Adrian Allan |
Review of SQL Server 2000 Programming |
SQL Server 2000 Programming claims to be a comprehensive guide to SQL Server 2000, and at a hefty 1390 pages, you can't argue with that. Being a programming guide, it concentrates only on issues that affect an SQL Server developer, but it still covers topics such as Database Administration to a reasonable level. Read more... By James Crowley |
Database Design Guidelines and Rules of Thumb |
Primary Keys You have three choices for defining the primary key for most tables: a 'natural' key, a system generated or 'internal' key, and (for smaller lookup tables) a mnemonic code. Internal ID numbers Rule of thumb: for any table over 100 records, use a system-generated number as the primary key. Read more... By Thomas B. Cox |
Beginners Guide To MySQL and PHP |
We've assembled a series of thoughts and examples based upon my own experience using Php 3.0 and MySql. Our goal is that it will aid any beginners in jumping over the common obstacles that hinder progress at the earliest stages of Php/MySql implementation. Read more... By W.J. Gilmore |
Just SQL Part II - The Simple SELECT |
At the core of most queries is an underlying table structure. Part II discusses how we can issue the most basic of SELECT statements to extract information from a database table. Read more... By James F. Koopmann |
Just SQL Part I - Introduction |
How many have you asked yourself what SQL is all about anyway? Join me as I begin a venture down the road of understanding SQL and how to take advantage of this language. Read more... By James F. Koopmann |
Upgrade Oracle 9i RAC to Oracle 10g RAC |
VThis article provides the procedures for converting Oracle 9i (9.2.0.4) RAC to Oracle 10g (10.2.0.1) RAC on Red Hat Enterprise Linux 3 (RHEL3). Read more... By Vincent Chan |
The True Test of a Good DBA |
There are a number of reasons why good DBA’s tend to be among the better paid folks in a software development shop and always considered among the least expendable in a any intensive production computing environment. Read more... By Bill Wunder |
Evaluating DBA Job Applicants in an OCP World |
Not long ago, weeding through DBA applicants with a tech interview was a straightforward process. You'd ask candidates 200 or so technical questions. If they got 100 correct answers, you knew they'd been around the block; 150 or more and you knew you were on Read more... By Robert Hamel |
.NET/OOP Primer for SQL Server CLR Integration |
One of the all new pieces of SQL Server 2005 is Common Language Runtime (CLR) integration. CLR integration extends the database to improve computational performance, text manipulation, and access to system resources outside Read more... By Bill Wunder |
The Seven Deadly Habits of a DBA |
Calling widespread bad habits in database administration "deadly" may seem extreme. However, when you consider the critical nature of most data, and just how damaging data loss or corruption can be to a corporation, "deadly" seems pretty dead-on. Read more... By Paul Vallee |
Building a Hybrid Data Warehouse Model |
As suggested by this reference implementation, in some cases blending the relational and dimensional models may be the right approach to data warehouse design. Read more... By James Madison |
Keep a check on your IDENTITY columns in SQL Server |
The IDENTITY columns, or 'auto number' columns as some people call them, are auto incrementing columns provided by SQL Server. There can only be one IDENTITY column per table. You just have to provide a base value, and an increment value, and SQL Server will take care of incrementing this column automatically. Read more... By vyaskn |
MDX Essentials: Set Functions: The MeasureGroupMeasures() Function |
This article is a member of the series, MDX Essentials. The series is designed to provide hands-on application of the fundamentals of the Multidimensional Expressions (MDX) language, with each tutorial progressively adding features designed to meet specific real-world needs. Read more... By William Pearson |
MySQL Failover Strategy using State Management, introducing MPP - Part 1 |
Having a strategy for failover has become almost standard in the business world. Whether it is a total site failover from a NOC in one city to another, or just a simple redundant server Read more... By Russell E Glaue |
Reporting with the Familiar |
Having a strategy for failover has become almost standard in the business world. Whether it is a total site failover from a NOC in one city to another, or just a simple redundant server Read more... By Mark Rittman |
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