Ok, I can see that now. If the record doesn't exist in the tracked table, it can't meet the window criteria.
The one way I see to get around this, in the absense of subselects, is to retrieve the tracked data that meets the window criteria into a temporary table. Right? -----Original Message----- From: Johnson, Gregert [mailto:[EMAIL PROTECTED]] Sent: Wednesday, October 03, 2001 10:03 AM To: [EMAIL PROTECTED] Subject: RE: Left Join problem It looks to me as though the "tracked.window=137" condition is suppressing output of any "available" rows which do not have a target match in "tracked" - tracked.window would = NULL in those cases. --Greg Johnson -----Original Message----- From: George Eric R Contr AFSPC/CVYZ [mailto:[EMAIL PROTECTED]] Sent: Wednesday, October 03, 2001 11:50 AM To: [EMAIL PROTECTED] Subject: Left Join problem I'm not getting the behavior I expect from this select. SELECT available.target, tracked.sensor FROM available LEFT JOIN tracked ON available.target=tracked.target WHERE available.window=137 AND tracked.window=137 AND available.sensor=8; Now, I know for this window, that there are 25 records for sensor 8 in the available table: SELECT count(*) FROM available WHERE window=137 AND sensor=8; count(*) 25 Now in the tracked table, some of the targets that are available to sensor 8 are actually tracked by another sensor, and some are not tracked at all. I expected the left join to show me which targets that are available to target 8 are tracked by which sensor, with NULL values in the right column for targets that are left untracked. I get half of that. My result set has 20 records. It correctly shows which sensor tracked which target. It doesn't show the 4 untracked targets at all? Ideas? Thanks Eric --------------------------------------------------------------------- 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 --------------------------------------------------------------------- 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
