Return a value if no record is found

Question

I have this simple statement that works:

SELECT idnumber FROM dbo.database WHERE number = \'9823474\'

If the number does not exist anywhere

Answer 1

To make it more simplier, this should work fine. If you assign this to a variable based on the datatype of your idnumber than you would be able to evaluate whether the value is null or the actual idnumber return.

SELECT ISNULL(
      (
         SELECT idnumber 
         FROM dbo.database 
         WHERE number = '9823474'
      ), NULL)