please notice that in 2nd query i sent, there's same table linked twice, because i need to link tree-like records.
how do i delete records from 1st table and not 2nd if they have same real name? like this: DELETE tasks FROM tasks as t_child LEFT JOIN tasks as t_parent ON t_child.parent_id=t_parent.task_id WHERE t_parent.task_id IS NULL -----Original Message----- From: Sergei Golubchik [mailto:[EMAIL PROTECTED]] Sent: Monday, October 22, 2001 3:52 PM To: Moshe Gurvich Cc: [EMAIL PROTECTED] Subject: Re: how to sub-select?.. Hi! On Oct 22, Moshe Gurvich wrote: > yeah, noticed it after clicked send.. > > let's say i upgrade to MySQL 4.0 and run this query: > > DELETE FROM tasks as t_child LEFT JOIN tasks as t_parent ON > t_child.parent_id=t_parent.task_id > WHERE t_parent.task_id IS NULL > > > will this work? no. > meaning it will delete records from 1st mentioned table in JOIN structure? Why waste the time guessing ? It's in the manual. Online manual is for 4.0, so you need not even download mysql-4.0 to read the manual. See my example - you have to put tables to delete from between DELETE and FROM : DELETE followups FROM followups LEFT JOIN tasks USING(task_id) WHERE tasks.task_id IS NULL; There can be several tables there - it's multi-table delete, after all :-) Access syntax is supported too: DELETE followups.* FROM followups LEFT JOIN tasks USING(task_id) WHERE tasks.task_id IS NULL; > Hi! > > On Oct 22, Moshe Gurvich wrote: > > thank you very much; > > > > i'm using right now v3.23 as recommended for production servers, but > > anyway.. > > > > now, using the way you suggested, will this work: > > > > DELETE FROM tasks > > FROM tasks as t_child LEFT JOIN tasks as t_parent ON > > t_child.parent_id=t_parent.task_id > > WHERE t_parent.task_id IS NULL > > > > thanx :) > > It won't work - note two FROM clauses. > > Multi-table deletes are available in 4.0 only. > In 3.23, I'm afraid, you have to do it in application :-( > > > On Oct 22, Moshe Gurvich wrote: > > > so what's the remedy? > > > how to do this task in MySQL without using subselects? > > > > > > > delete from followups where task_id not in (select task_id from tasks) > > > > > > > > Multi-table deletes (MySQL 4.0.0+) > > > > DELETE followups FROM followups LEFT JOIN tasks USING(task_id) WHERE > > tasks.task_id IS NULL; > > > > Regards, > > Sergei > > Regards, Sergei -- MySQL Development Team __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Sergei Golubchik <[EMAIL PROTECTED]> / /|_/ / // /\ \/ /_/ / /__ MySQL AB, http://www.mysql.com/ /_/ /_/\_, /___/\___\_\___/ Osnabrueck, Germany <___/ --------------------------------------------------------------------- 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 --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.281 / Virus Database: 149 - Release Date: 9/18/2001 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.281 / Virus Database: 149 - Release Date: 9/18/2001 --------------------------------------------------------------------- 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
