Comments on: Cleaning up orphaned records in MySQL

By: Arian

Arian — Thu, 22 May 2008 15:51:57 +0000

whoops more research found this…
Thanks for the info! really useful
”
For the first multiple-table syntax, only matching rows from the tables listed before the FROM clause are deleted. For the second multiple-table syntax, only matching rows from the tables listed in the FROM clause (before the USING clause) are deleted. The effect is that you can delete rows from many tables at the same time and have additional tables that are used only for searching:

DELETE t1, t2 FROM t1, t2, t3 WHERE t1.id=t2.id AND t2.id=t3.id;
“

By: Ryan Stille

Ryan Stille — Thu, 22 May 2008 15:48:20 +0000

Yes – that documentation appears to support the syntax I used in this article, no?

By: Arian

Arian — Thu, 22 May 2008 15:45:24 +0000

Just saying cause i was looking at the MYSQL5.1 manual

DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
tbl_name[.*] [, tbl_name[.*]] …
FROM table_references
[WHERE where_condition]

By: Ryan Stille

Ryan Stille — Thu, 22 May 2008 15:23:44 +0000

No, thats not a mistake. You are right that in a normal delete you would just say “DELETE FROM subTable”. But we are doing a join here. So I believe doing it this way indicates which table from all the tables listed you want to delete from. I’m not 100% sure if its required or not, maybe it will just delete from the first table listed if you didn’t explicitly say “DELETE subTable”.

By: Arian

Arian — Thu, 22 May 2008 15:19:34 +0000

‘DELETE subTable FROM subTable’, is that a mistake?
thought MYSQL syntax was ‘DELETE FROM subTable’?