As we're on this topic in another thread right now:
Say I have a SELECT query from more than one table and with some =
conditions, does it matter in what order I enter the tables in the FROM =
clause and in what order the WHERE conditions appear in my query? Or =
does it make any difference if I use WHERE or HAVING? (I see that MS =
Access likes those HAVINGs...)
Of course my tables contain (maybe very much) more than some 100 records =
and are well-indexed, I believe.... but that's not my question for now.
I guess, the MySQL optimizer reads the table and column names in the =
specified order and tries to process them the same way, right? Or it =
joins the tables in my given order... And when are the resulting records =
reduced by matching against my conditions? Maybe someone can tell me a =
little bit about performance gains just by doing some 'manual query =
optimization' :)
Yves Goergen
www.unclassified.de
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