From: Michael Widenius
Date: March 25 1999 10:22am
Subject: Query performance with functions
List-Archive: http://lists.mysql.com/mysql/941
Message-Id: <14074.3628.286545.403340@monty.pp.sci.fi>
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>>>>> "Curt" == Curt W Zirzow <curt@stripped> writes:

Curt> Hello,
Curt>  I noticed that in the latest version of mysql that you no longer can 
Curt> use the column alias inside the where clause. Does this (ie. In the 
Curt> following query) cause the function be called in both cases or would 
Curt> it be called once and aliased in the where clause? 

Curt> select function(column) as column_alias
Curt> from table
Curt> where function(column) > 0

Hi!

The above has never worked in any MySQL version and is not even
allowed according to the ANSI SQL standard.

Regards,
Monty

PS:  You can always use HAVING ...