Tokens in Pear DB query

[sellers]

Has anyone ever used tokens with the DB::query method?

The code following works fine:

$psurname = 'Smith';

$sql = "...
WHERE per.surname like '$psurname' 
...";

$result = $db->query($sql);

But when I attempt this :

$psurname = 'Smith';

$sql = "...
WHERE per.surname like ?
...";

$result = $db->query($sql, array($psurname));

I get no records returned from the database, and when I try:

$psurname = 'Smith';

$sql = "...
WHERE per.surname like !
...";

$result = $db->query($sql, array('Smith');

I get the following error:

DB Error: mismatch

Has anyone managed to get this use of tokens to work?