query with "IN" parameter

@utodev,

Any reason why you don't upgrade to CI 3.1.x?
Anyway, my suggestion is to not use the ? but use a variable (of course not forgetting to vet the data prior to putting it in the query).

$x = "'a','b','c'";
$y =3;
$sql = 'SELECT x,y,x from TABLE WHERE x IN ('.$x.') and y=?';
$result = $this->db->query($sql, array($y));