$db->hide_errors() still reveals query

With php.ini display_errors = OFF and with $db->hide_errors() included in the script, if I knowingly submit a bad query, the SQL is displayed at the top of the page. I use a lot of input filtering and specific form field validation to eliminate it, but is there a way to make sure it will never slip through and display the query? Tweak a MySQL setting perhaps?

Example:

[include ezsql]
$db->hide_errors();
$db->query("SELECT foo FROM bar");

displays:
SELECT foo FROM bar
but does not display MySQL Warning-type error msg.