[solved!] A Database Error Occurred

[eluser]maria clara[/eluser]
i commented for a while the $data['client_id']

Code:

$this->db->where('client_id'/*, $data['client_id']*/);
        $this->db->where('status !=', '2');
        $this->db->where('is_deleted', '0');
        $sales = $this->db->get('ar_sales')->row_array();
        
        $sales['balance'] = $sales['sales'] - $sales['payment'] - $sales['credit'] + $sales['debit'] - $sales['return'];
        
        $this->db->where('cust_id'/*, $data['client_id']*/);
        $this->db->update('maint_customers', $sales);

and now it doesn't show the error. i still figuring out where can that be placed??