In the last versions of postgres, do :
INSERT INTO blah RETURNING blah_id
No need to worry about sequences or anything. It inserts, then it returns
the inserted id, as the name says.
Very much unlike MySQL where insert_id() returns the id of the last
insert, even if it was done in an ON INSERT TRIGGER so isn't what you want
at all !
On Fri, 01 Jun 2007 21:39:49 +0200, Bill Moran <wmoran@xxxxxxxxxxxxxxxxx>
wrote:
In response to lawpoop@xxxxxxxxx:
Hello all -
I'm working on a site with PHP and Postgres, coming from a MySQL
background.
I was looking for an equivalent to the mysql_insert_id() function, and
a site recommended this:
function postg_insert_id($tablename, $fieldname)
{
global connection_id;
$result=pg_exec($connection_id, "SELECT last_value FROM ${tablename}_
${fieldname}_seq");
$seq_array=pg_fetch_row($result, 0);
return $seq_array[0];
}
It relies on pg's sequencing ability.
However, I wondered, if I were in an environment where there were many
concurrent inserts, would it be possible that I didn't get the serial
number of the insert that *I* just did? That if I do an insert, and
several inserts happen after mine, wouldn't I get the id of the latest
row, which is several inserts after mine?
Don't do that. Please let us know what site recommended that so I can
send an email to the author correcting them.
Instead, do SELECT currval('<seqname>'), which is guaranteed to be
isolated
from other sessions.
If you use the code above, sooner or later you're going to get bit.
