Over the last 30+ years of working with SQL Server, I have seen a lot of interview questions relating to SQL Server. I have been on both sides of the interview table, sometimes wondering what the person on the other side of the table was asking. As a SQL Server developer do you feel that you were asked good questions during your interview?
There are 3 questions that I really like when interviewing candidates for SQL Server developer positions.
- I only ask this one when people claim that they have performance tuning experience, which I would hope that most senior developer candidates would have.
Can you explain to me what in index is and what the differences are between a clustered index and a non-clustered index?
What I love about this question is that it not only requires the basic technical knowledge of indexes, but it also shows how well someone can explain more complex topics. I have really be surprised at the answers I have seen to this question. - My next favorite is relating to joins, and I ask the following:
Can you explain the difference between an inner join and an outer join?
This leads to how much they actually know about connecting tables. Do you mean an left outer join, right outer join, full outer join? What about full outer joins with exclusion? When asking this question I have been amazed with how many people just made up something when it was clear that they did not know what I was asking about. - My last favorite interview question is for anyone claiming to be experience, or senior, or lead.
Tell me about a time that something went horribly wrong, and what you did to recover from that?
If someone claims that they have never had something go horribly wrong in the database, they are either not very experienced, or they are not telling the truth.
So I want throw this question out to you our blog readers… What is your favorite interview question, and this can come from experience on either side of the interview table, the candidate or the interviewer?
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The questions I like are use cases for for designs that are outside of best practices. It demonstrates the candidate has an understanding of best practices, but is flexible to consider designs outside of best practices. For example, what is a good use case for a table without a primary key and explain why. Or, a good use case for entity-attribute-value (EAV) table structure. A common answer for these are there are none. Occasionally, I have heard “I don’t know,” which I follow up with questions to determine if the candidate believes there are none, but will not be bold enough to state that there are none. Occasionally, I will have a candidate that will provide good use cases.
Robert,
I really like the way you are thinking with those questions. The key is really where the conversation goes when they are explaining why. That can get really interesting.
Thanks for your comments
– Steve Stedman