RE: Help - Tuning SQL

The Rule-based optimizer is influenced by the order of your WHERE statements ... it won't re-arrange them to improve performance.

If you're using the cost-based optimizer, I believe it will decide what order to process the WHERE statement clauses, based on what it decides is the most efficient access method.

Dave

> -----Original Message-----
> From: Armstead, Michael A [mailto:maa25681_at_GlaxoWellcome.com]
> Sent: Wednesday, February 28, 2001 1:51 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Help - Tuning SQL
>
>
> I've got some simple questions on tuning SQL. Please reply
> with references,
> I'm not looking for guesses.
>
> * If you have a SELECT statement with a WHERE clause and 2 AND
> clauses, which one is processed first, the WHERE clause, the first AND
> clause, or the second AND clause?
> * Is there any performance loss in using "<>" over "!="?
>
> Michael Armstead
> Database Administrator, OCP-Certified
> Corporate & Finance Information Systems
> Glaxo SmithKline
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Armstead, Michael A
> INET: maa25681_at_GlaxoWellcome.com
>
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