MySQL Forums
Forum List  »  Optimizer & Parser

WHERE clause processing
Posted by: Maxx Kazimieszko
Date: November 15, 2005 05:20PM

Greetings!

Does anyone know - as I can't seem to find it in documentation - how the multiple expressions in WHERE clause are processed?

I mean, if WHERE clause contains the following:
field1=val1 AND field2=val2
are both parts of the conjunction processed?
If for given row first expression (field1=val1) is FALSE, there is no need to process the other one
- the whole row can be immediately excluded from the results set, isn't it so?
This would be particularly useful if results of two subqueries were to be calculated...

Kind regards,
Maxx

Options: ReplyQuote


Subject
Views
Written By
Posted
WHERE clause processing
3160
November 15, 2005 05:20PM
2175
November 15, 2005 07:32PM


Sorry, you can't reply to this topic. It has been closed.

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.