SQL Server: How to check if the value of returned field is not null

Question

I have SQL statement as follows:

SELECT  ReturnDate
FROM    <joins>
WHERE   <conditions>

How to check if ReturnDate is not null?

Answer 1

You can use CASE with IS NULL (or IS NOT NULL):

SELECT CASE 
         WHEN ReturnDate IS NULL THEN 'It is null' 
         ELSE 'It is not null' 
       END AS IsItNull 
FROM   dbo.tablename ....

If you need to filter for NULL/NOT NULL values you can also use IS NOT NULL:

WHERE ReturnDate IS NOT NULL  ...