SQL Inner Join On Null Values

Question

I have a Join

SELECT * FROM Y
INNER JOIN X ON ISNULL(X.QID, 0) = ISNULL(y.QID, 0) 

Isnull in a Join like this makes it slow.

Answer 1

This article has a good discussion on this issue. You can use

SELECT * 
FROM Y
INNER JOIN X ON EXISTS(SELECT X.QID 
                       INTERSECT 
                       SELECT y.QID);