Query fails with PostgreSQL

The function

function profile_taxonomy_get_vocabulary_id($field) {
$sql = "SELECT * FROM {profile_taxonomy} WHERE fid = '%s'";
return db_fetch_object(db_query($sql, $field))->vid;
}

issues an error that the input syntax for integer is illegal.
The following change solves the problem for PostgreSQL and hopefully doesn't harm MySQL-installations.

function profile_taxonomy_get_vocabulary_id($field) {
$sql = "SELECT * FROM {profile_taxonomy} WHERE fid = %d";
return db_fetch_object(db_query($sql, $field))->vid;
}

Regards
Conni