Re: join query question

This depends on a number of factors, mostly the size of A and B and the uniqueness of empnum in these tables.

What is your situation? Do you have indexes on empnum?

All the mentioned methods may have disadvantages for a particular constellation. So please specify

• the size in rows of A and B
• if empnum is unique in A
• if empnum is unique in B
• if there is an index A (empnum, ...)
• if there is an index B (empnum, ...)
• How many rows do you expect in fraction of A? If you would expect a result set close to the empty set this would mean that A and B are nearly the same. But if a considerable amount of A (say 10 % of A) is expected as a result set then some performance results will change.

Martin

vk02720 wrote:
>
> table A and table B both have a common field empnum.
> What is the most optimal query to get the data from table A which is not in the
> table B using empnum ?
>
> TIA
Received on Fri Jun 22 2001 - 12:27:01 CDT