Is using SELECT Max(ID) FROM table safer than using SELECT last_insert_id(), where they run as 2 separate queries?
I'm concerned that before the last_insert_id() can run, another insert will take place.
+8
A:
Is using SELECT Max(ID) FROM table safer than using SELECT last_insert_id()
Definitely not, never! LAST_INSERT_ID() exists exactly for the reason you state: Other clients could have made other inserts. LAST_INSERT_ID() always gives you the last inserted ID on the current connection.
Unicron
2010-07-05 15:11:53
how does connection pooling affect this?
Yisroel
2010-07-05 15:31:52
Agreed, but remember that you have to be using the same connection, and it must not have been closed and re-opened. You should always run this directly after the INSERT command, before doing anything else - make it a habit, and then when you need the value, you already have it stored in a variable... :)
Dave Rix
2010-07-05 15:33:56
Are you connecting to the db through the command line, or using a language such as PHP? that can make a difference...
Dave Rix
2010-07-05 15:34:53
i'm using classic asp
Yisroel
2010-07-05 15:36:01
+3
A:
Using select max(id) is just asking for trouble. It's only a matter of time before two inserts would happen near-simultaneously and you would start to see some craziness in your data.
joeynelson
2010-07-05 15:24:11
Because of isolation levels, typically SELECT is given higher priority - so `SELECT MAX(id) ...` can occur before an insert. Not good if I can select the value for my insert, just before your insert occurs...
OMG Ponies
2010-07-05 16:04:52