How to check if a column is empty or null using SQL query select statement?

Question

How do I check if a column is empty or null using a SQL select statement?

For instance, if I want to check:

select * from UserProfile WHERE PropertydefinitionID in (40, 53) and PropertyValue is null or empty 

Answer 1

Does this do what you want?

SELECT * FROM UserProfile WHERE PropertydefinitionID in (40, 53)   AND (    PropertyValue is NULL         or PropertyValue = '' ); 

Answer 2

Here's a slightly different way:

SELECT * FROM UserProfile WHERE PropertydefinitionID in (40, 53)   AND (LEN(ISNULL(PropertyValue,'')) = 0)