codeigniter - compare values - codeigniter

Question

I need to compare two values in a table: cliente and nro_cuota, if both exist I don't want to add it.
Here is my code
$crud = new grocery_CRUD();
$crud->set_theme('datatables');
$crud->set_table('cobranzas');
$crud->set_subject('Cobranzas');
$crud->set_language('spanish');
$crud->required_fields(
'id',
'cobrador',
'cliente',
'nro_cuota'
);
$crud->columns(
'cobrador',
'cliente',
'nro_cuota'
);
$crud->set_relation('cobrador', 'cobradores', 'apellido_nombre');
$crud->set_relation('cliente', 'clientes', 'apellido_nombre');
$output = $crud->render();
$this->load->view('cobranzas/cobranzas_v', $output);
}catch(Exception $e){
show_error($e->getMessage().' --- '.$e->getTraceAsString());
}
}
and I wrote a model, I`m not sure if this is the right way, but I don't know how I must call it
class Compare_values_model extends CI_Model
{
public function compare($id)
{
$this->db->select('"SELECT * FROM `cobranzas` WHERE `cliente` = '$cliente' AND `nro_cuota` = '$nro_cuota'"');
if ($query->num_rows() > 0) {
return true;
} else {
return false;
}
}
}
Hope can help me I couldn't find some examples on internet to learn more, thanks in advance.

Answer 1

You said I need to compare two values in a table: cliente and nro_cuota, if both exist I don't want to add it. But you are matching the variables with fields. So just check not equal as below:
$query = $this->db->query("SELECT * FROM `cobranzas` WHERE `cliente` <> '$cliente' AND `nro_cuota` <> '$nro_cuota'");
Note: Remove extra single quote in your query