This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Intro
Question:
You need to filter rows being returned by a query.
When should you use a HAVING clause rather than a WHERE clause?
Answer:
A WHERE clause is used to filter the rows from the source (usually a table).
2025-05-24
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Administrator Level: Medium
Question:
You are considering adding an index to a table.
You have heard that adding indexes slows down UPDATE commands.
Does adding an index always slow down updates? If so, why? If not, why not?
2025-05-20
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Administrator Level: Medium
Question:
Your database application has been suffering from signficant blocking issues.
One developer has suggested enabling RCSI for the database.
If you do that, what’s different about how the database would operate?
What code changes are needed to use it?
2025-05-16
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Intro
Question:
You need to extract the hour component from a datetime value.
Which function should you use?
Answer:
To do this in SQL Server, you should use the DATEPART function.
2025-05-12
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Intro
Question:
You have a table named HumanResources.Employees. Some employees are managers.
You want to join the table to itself to join employee rows with their manager rows.
What is required when you join a table to itself, that is not required for joining separate tables?
2025-05-10
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Intro
Question:
You are writing a function that needs to process UTF-8 data. It takes one input parameter named @ValueToProcess that varies in length.
Which data type should you use for the @ValueToProcess parameter?
Answer:
2025-05-08
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Medium
Question:
You have a value in a variable named @NewValue. The data type is varchar(20).
You want to check if the value in the string is an integer and could be cast to an integer.
2025-05-06
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Intro
Question:
You want to call a procedure that counts the number of customers in a particular city.
You use the following code:
DECLARE @NumberOfCustomers int;
EXEC dbo.GetNumberOfCustomers
@City = N'Brisbane',
@NumberOfCustomers = @NumberOfCustomers;
SELECT @NumberOfCustomers;
No matter which city name you pass in the code, the selected count is NULL.
2025-05-04
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Medium
Question:
You have a series of very similar SQL queries in an application.
You notice that one of them includes an OPTION LABEL clause.
What would this be used for?
Answer:
OPTION LABEL allows you to apply a label to an instance of a query. That then makes it easy to trace executions of the query using tools like Extended Events or SQL Server Profiler.
2025-05-02
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Administrator Level: Medium
Question:
Your team is considering a design where a small number of tables would each have a very large number of columns.
One developer has suggested making the columns SPARSE where another has suggested just making them NULLable.
2025-04-28