Generates a WHERE field IN (‘item’, ‘item’) SQL query joined with AND if appropriate,
$this->db->where_in()
ex : $this->db->where_in('id', array('1','2','3'));
Generates a WHERE field IN (‘item’, ‘item’) SQL query joined with OR if appropriate
$this->db->or_where_in()
ex : $this->db->where_in('id', array('1','2','3'));