Questions to ask a SQL Server database developer applicant

Questions to ask a SQL Server database developer applicant

Can you give me an overview of some of the database objects available for use in SQL Server 2000?

You are looking for objects such as: tables, views, user-defined functions, and stored procedures; it's even better if they mention additional objects such as triggers. It's not a good sign if an applicant cannot answer this basic question.



What is an index? What types of indexes are available in SQL Server 2000?

Any experienced database developer should be able to answer this question with ease. Some of the less-experienced developers will be able to answer it, but with a little less clarity.
In its most simple terms, an index is a data structure used to provide quick access to data in a database table or view. In SQL Server, they come in two flavors: clustered and non-clustered. Clustered indexes store the data at the leaf level of the index. This means that whichever field(s) in your table are included in the clustered index, they will be stored in an orderly fashion in the table. Because of this sorting, you can only have one clustered index per table. Non-clustered indexes contain a row identifier at the leaf level of the index. This row identifier is a pointer to a location of the data on the disk. This allows you to have more than one non-clustered index per table.



What does NULL mean?

The value NULL is a very tricky subject in the database world, so don't be surprised if several applicants trip up on this question.
The value NULL means UNKNOWN; it does not mean '' (empty string). Assuming ANSI_NULLS are on in your SQL Server database, which they are by default, any comparison to the value NULL will yield the value NULL. You cannot compare any value with an UNKNOWN value and logically expect to get an answer. You must use the IS NULL operator instead.