Complex Sql don't work in $this->db->query()

[eluser]abmcr[/eluser]
I have try to use a complex query : this sql work fine into the SQL tab of phpadmin... and not into CI.

Code:

$sql="CREATE TEMPORARY TABLE tmptable
SELECT id FROM bacheca AS A ORDER BY id DESC LIMIT 30;
DELETE bacheca FROM bacheca WHERE id NOT in (SELECT * FROM tmptable)";
$this->db->query($sql);

The error is

Code:

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ';DELETE bacheca FROM bacheca WHERE id NOT in (SELECT * FROM tmptable)' at line 1

CREATE TEMPORARY TABLE tmptable SELECT id FROM bacheca AS A ORDER BY id DESC LIMIT 30;DELETE bacheca FROM bacheca WHERE id NOT in (SELECT * FROM tmptable)

Any suggestion? Thank you in advance.... ciao!