$names = array('Frank', 'Todd', 'James');
$this->db->where_not_in('username', $names);
// Produces: WHERE username NOT IN ('Frank', 'Todd', 'James')
$names = array('Frank', 'Todd', 'James');
$this->db->or_where_in('username', $names);
// Produces: OR username IN ('Frank', 'Todd', 'James')