How to return default value from SQL query

Question

Is there any easy way to return single scalar or default value if query doesn\'t return any row?

At this moment I have something like this code example:

Answer 1

You can drop the if statement using following construct but that doesn't necessarely mean it is better.

SELECT Name FROM Users WHERE Id = @UserId UNION ALL 
SELECT 'John Doe' WHERE NOT EXISTS (SELECT Name FROM Users WHERE  Id = @UserId)