Count rows in an inverted way in php

I am trying to add the values of a row from bottom to top but I can not do it, I have tried with a for loop with the array_reverse property and with the ORDER BY property but I can not find the correct result. In the array_reverse I invert the values of the column but not the row as I pretend in the other cases does nothing. This is the code:

 //código para hacer el conteo que funciona 
 $aColumns = array('numero_comprobante');  
     $sTable = "comprobante";
     $sWhere = "";  

     $sWhere = "WHERE (";
        for ( $i=0 ; $i<count($aColumns) ; $i++ )
        {
            $sWhere .= $aColumns[$i]." LIKE '%".$q."%' OR ";
        }
        $sWhere = substr_replace( $sWhere, "", -3 );
        $sWhere .= ')';

    $sWhere.=" order by codigo desc";
    // a partir de acá debería de empezar con el conteo por filas invertido
    $sql1= "select * from comprobante where descripcion='".$descripcion."' order by codigo asc";        
    $query1 = mysqli_query($con, $sql1);
    $fila = mysqli_num_rows($query1);  
            if ($fila==1) {
            $cantidades=$cantidad;

        }   
        else {

        if ($id_tipo==3) {
            $cantidades-=$cantidad;
        }           
        if ($id_tipo==2)  {
        $input  = array($cantidad, array($numero_comprobante));
        $reversed = array_reverse($input); 
        print_r($reversed);
        $cantidades+=$cantidad; 

        }

        if ($id_tipo==1)  {
            $cantidades-=$cantidad;             
        } 
        }

Note: The $ id_type corresponds to purchase invoice, sales invoice or payment order. - The sum is only made when the descriptions match.