Is there any more efficient to update the database value?
Running a query within a loop is usually not a good idea. Instead, you can set the new value to qty + $qty by concatenating the variable to the string.
function updateQty($qty, $kode) { $this->db->set('qty', 'qty + '.(int)$qty); $this->db->where(['kode' => $kode, 'username' = >$this->session->userdata('username')]); $this->db->update('temp'); }