NOT IN vs NOT EXISTS

Question

Which of these queries is the faster?

NOT EXISTS:

SELECT ProductID, ProductName 
FROM Northwind..Products p
WHERE NOT EXISTS (
    SELECT 1 
    FROM         


        

Answer 1

I was using

SELECT * from TABLE1 WHERE Col1 NOT IN (SELECT Col1 FROM TABLE2)

and found that it was giving wrong results (By wrong I mean no results). As there was a NULL in TABLE2.Col1.

While changing the query to

SELECT * from TABLE1 T1 WHERE NOT EXISTS (SELECT Col1 FROM TABLE2 T2 WHERE T1.Col1 = T2.Col2)

gave me the correct results.

Since then I have started using NOT EXISTS every where.