Dan Jones <[EMAIL PROTECTED]> wrote: > How do I update a table to remove orphaned references to a second > table? I've deleted rows in the second table, which has a unique > auto_increment key. The first table now has references to keys that no > longer exist. I need to update the first table, setting the value to > NULL where the referenced key no longer exists. Something like: > > UPDATE table1 SET table2ID = NULL WHERE table1.table2ID NOT FOUND IN > table2.ID; > > The NOT FOUND IN isn't SQL, of course, but I'm not sure what should go > there.
If you have MySQL server version 4.0.4 or newer, you can do something like: UPDATE table1 LEFT JOIN table2 ON table1.table2ID=table2.ID SET table1.table2ID=NULL WHERE table2.ID IS NULL. -- For technical support contracts, goto https://order.mysql.com/?ref=ensita This email is sponsored by Ensita.net http://www.ensita.net/ __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Victoria Reznichenko / /|_/ / // /\ \/ /_/ / /__ [EMAIL PROTECTED] /_/ /_/\_, /___/\___\_\___/ MySQL AB / Ensita.net <___/ www.mysql.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
