WHERE field = XXX vs WHERE field != XXX : Performance the same? 1

[jpo245]

Hi everyone, is there any performance difference btw the following WHERE criteria.

WHERE abcfield = 'XXXX'

vs

WHERE abcfield <> 'XXXX'

A)There are same number of records that for each of the above criteria
B) abcfield is indexed.

This has been puzzling me. At first i thought that WHERE abcfield <> 'XXXX' would be slower, but thinking abt how mysql uses indexes, it might not necessarily be the case.

Thanks!!!

 

[TonyGroves]

If you issue a query in the form:[tt]
EXPLAIN SELECT * FROM tblname WHERE ...[/tt]
it will show you what indexes it uses.

Also, when you run the actual query using either the "mysql" command-line client or MySQL Query Browser, the length of time it took is shown. You would want to run each query a few times, using "RESET QUERY CACHE" between each run.