>>Another sql question: How would one say "In table A, but not in table B" in sql?
>>thanks, Randy
>
>

>select tableA.* from TableA T1 LEFT JOIN  TableB T2 on T1.PK = T2.FK where T2.FK IS NULL

>
>this usually performs better than
>

>select * from TableA where PK not in (select FK from TableB)

>
>See interesting discussion at
>http://blog.sqlauthority.com/2008/04/22/sql-server-better-performance-left-join-or-not-in/

Noami,

You forgot the third possiblity

SELECT * FROM TableA T1 WHERE NOT EXISTS(SELECT 1 FROM TableB WHERE FK = T1.PK)

The EXISTS() clause is a very important and often underestimated insturment in resolving these types of queries. Above all it is a more natural translation of the asked question: Give me everything from table A which does not have records in table B.




Walter,