10 SQL Server database developer interview questions and answers

Interviewing for developer jobs with an SQL Server specialism can be daunting, but if you know what questions you’ll likely face, you can prepare to answer them in advance.

Here are just 10 questions for SQL database developer interviews and the answers you need to navigate them successfully.

What is deadlocking?

Interviewers will want to know that you understand the things which can impact server performance, and deadlocking is a common conundrum.

Read SentryOne’s article to learn more about SQL deadlocks before the interview, but mostly remember that when resources are monopolized by two or more processes with exclusive locks on them, one will get the boot.

Point out that not all deadlocks are problematic, and so it is down to developers to fix genuine issues while knowing which instances of deadlocking are not worth worrying about.

What is the purpose of temp tables?

For an SQL database to handle information concurrently in an efficient, swift way, temp tables are invaluable.

There are both local temp tables created for as long as an individual user is connected to the database, as well as global temp tables that persist until every user has disconnected. This is a good opportunity to discuss TempDB as well.

What is a transaction?

If an SQL command represents one facet of database manipulation, then a transaction is a chain of these commands which can only execute in full if every unit it contains is capable of completing unhindered.

What are the different index types?

Talking about both clustered and non-clustered indexes, with the former being stored sequentially and the latter not impacting the order of the data it contains, could be necessary.

You might also take this opportunity to discuss index fragmentation and what this means to database performance.

Are there different ways to remove data from a table?

This is where you will need to explain the function of the truncate and delete commands. ‘Truncate’ offers speedy deletion of data contained in a table, while ‘delete’ deals with individual rows and takes heed of relevant triggers to remove info from elsewhere as necessary.

How can SQL code be optimized?

Lots of potential answers can be given here, but it is most useful to discuss the use of query execution plans, and how these can be displayed, accessed and analyzed from within SQL Server via the related dropdown menu.

Why is SQL Server Agent needed?

Scheduling is an important part of the SQL Server ecosystem, and the Windows-based Server Agent is in charge of orchestrating these duties as and when they are required. If the Agent encounters issues, tasks may fail.

Which port does SQL server use?

If you are tightly controlling TCP port access, it pays to know that SQL Server makes use of port 1433 by default. It’s another simple yet informative question interviewers may hit you with.

What is a view?

When you want to combine several tables or manage how they are accessed, then a view is a way of doing this virtually within SQL Server.

Data can be updated in this context, but liberal use of the WITH CHECK OPTION clause can prevent this from occurring in the case that the data isn’t within the remit of the view as defined by the developer.

What commands can help investigate database consistency?

Being able to quickly see how a database is performing is possible thanks to the Database Consistency Checker (DBCC) commands.

DBCC HELP will bring the main ones up, and they can be used to check things like disk allocation consistency and also to explore recent transactions.This is just a taste of questions you might face in a developer interview, so do as much preparation as possible to make a good impression.

Author: Editorial Team

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