It works differently in PostgreSQL, see database.pgsql.inc, or here:
http://api.drupal.org/api/function/db_last_insert_id

On Wed, Nov 4, 2009 at 7:07 PM, Jeff Greenberg <jeff@ayendesigns.com> wrote:
I'm confused with the db_last_insert_id function in database.mysql-common.inc.


The function is:


function db_last_insert_id($table, $field) {
 return db_result(db_query('SELECT LAST_INSERT_ID()'));
}


and I see no reason whatsoever for there to be any parameters, let alone required ones.