From: 
Date: July 24 1999 3:52pm
Subject: MySQL query optimisation
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Hi,
Does MySQL do the optimization
by not calling CONCAT 5 times in the following QUERY,
which I use to check for the keywords.

SELECT * from table_x WHERE
id=34 AND y=67 AND
(FIND_IN_SET('word1',CONCAT(field_1,field_2))>0 OR
 FIND_IN_SET('word2',CONCAT(field_1,field_2))>0 OR
 FIND_IN_SET('word3',CONCAT(field_1,field_2))>0 OR
 FIND_IN_SET('word4',CONCAT(field_1,field_2))>0 OR
 FIND_IN_SET('word5',CONCAT(field_1,field_2))>0)

It looks like no, but may be I am wrong.
This some times creates a problem because SQL does not have local variables.

Vladislav