codeigniter 3 where code example

Example 1: codeigniter where_not_in

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

Example 2: codeigniter where order by

$this->db->select('ae_users.employee_id, ae_users.emp_name, ae_users.emp_name2, ae_users.emp_name3');
		$this->db->from('ae_users');                
		$this->db->where_in('ae_users.employee_id',$employee_ids);
                $this->db->_protect_identifiers = FALSE; // stop CI adding backticks
                $order = sprintf('FIELD(ae_users.employee_id, %s)', implode(', ', $employee_ids));
                $this->db->order_by($order);
                $this->db->_protect_identifiers = TRUE; 
		$query =$this->db->get();
               // echo '<pre>'; print_r($this->db->last_query());exit;
		if ($query->num_rows()) {
			return $query->result_array();
		} else {
			return 0;
		}