From: Peter Brawley
Date: November 29 2005 1:32am
Subject: Re: comma-separated JOINS
List-Archive: http://lists.mysql.com/mysql/192285
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Matt,

 >When using JOINS by the simply supplying a comma separated list of 
tables in
 >the FROM clause, is the ON argument normally associated with a join 
intended
 >to be addressed in the WHERE clause, or should ON still be used?

There's no ON clause for a join specified by a WHERE clause, and that's 
one reason specifiying joins with JOIN ... ON ..  is almost always 
preferable--it entirely disambiguates the join for the writer, readers, 
and those others who later will have to divine what you meant :-) .

PB

-----

Matt Monaco wrote:

>When using JOINS by the simply supplying a comma separated list of tables in
>the FROM clause, is the ON argument normally associated with a join intended
>to be addressed in the WHERE clause, or should ON still be used?
>
>// Comma separated join
>SELECT u.*, a.city FROM users u, addresses a WHERE u.id=a.user_id;
>
>// Actual JOIN clause
>SELECT u.*, a.city FROM users u INNER JOIN addresses a ON u.id=a.user_id;
>
>
>// Query style in question
>SELECT u.*, a.city FROM users u, addresses a ON u.id=a.user_id;
>
>If not ON, is there at least another viable argument?  The reason I'm
>interested is for a query involving 5 or 6 tables and WHERE arguments which
>do not deal with the relationships.  I would like to assure the efficiency
>of this query.
>
>
>Thanks in advance,
>Matt 
>
>
>
>  
>


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