From: Dan Nelson
Date: May 27 2003 3:03am
Subject: Re: How to write this query pls?
List-Archive: http://lists.mysql.com/mysql/140841
Message-Id: <20030527030301.GA30427@dan.emsphone.com>
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In the last episode (May 27), Aamir Baig said:
> You would figure that an sql query like following would work (I
> modified it slightly as it needs to take into account the type
> column):
> 
> select P.personid ,
> SUM(CASE WHEN PH.type = 'PHN' THEN 1 ELSE 0 END) AS PHNC
> From Person P left outer join Phone PH
> ON P.personid
> Where PHNC = 0 group by Phone.personid;
> 
> But it says:
> ERROR 1054: Unknown column 'PHNC' in 'where clause'
> 
> I know it's something trivial, can't seem to place the finger at it
> though..

You can't use a column alias in the WHERE clause; you'll have to
duplicate the SUM expression.  See
http://www.mysql.com/doc/en/Problems_with_alias.html

-- 
	Dan Nelson
	dnelson@stripped