Sorry I should have made this a bit clear. I have to tables with users names in them. All I need is a list on the Usernames that are in one column but not the other. The problem is like Mr DuBois said, is that I get every possible match like a matrix (I think?). So how do I get the values that are just not it one column?
Thanks Simon -----Original Message----- From: Paul DuBois [mailto:[EMAIL PROTECTED]] Sent: 27 June 2002 05:00 To: Simon Green; Mysql (E-mail) Subject: Re: Cartesian Product At 13:22 +0100 6/26/02, Simon Green wrote: >Hi >When I run my MySQL question I get what I think is a cartesian product? > >SELECT table1,Username >FROM table1, table2 >WHERE table1.Username != table2.Username; > >If I just run'=' then no problem but it seems to what to match every thing >with every thing >and so I run out of memory. >Is there a way to do a distinct match? >Thanks >Simon What do you mean by "distinct match"? Your != query is effectively a cartesian product that retrieves all but the diagonal elements of the matrix. --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
