Sql query to set wordpress category

Hi I use an sql query to set all my post type to specify category and I use:

for($i = 0;$i<$count;$i++)
{
    if($i<22)
    {
    $order = "UPDATE wp_term_relationships 
                                  SET term_taxonomy_id='18' 
                                  WHERE object_id='$id[$i]'";

    $retval = mysql_query( $order, $conn );
    if(! $retval )
    {
      die('Could not update data: ' . mysql_error());
    }
    else
        echo 18;
    }
    else{
        if($i<178){
            $order = "UPDATE wp_term_relationships 
                                      SET term_taxonomy_id='15' 
                                      WHERE object_id='$id[$i]'";

        $retval = mysql_query( $order, $conn );
        if(! $retval )
        {
          die('Could not update data: ' . mysql_error());
        }
        else
            echo 15;
        }


        else{
            $order = "UPDATE wp_term_relationships 
                                              SET term_taxonomy_id='29' 
                                              WHERE object_id='$id[$i]'";

                $retval = mysql_query( $order, $conn );
                if(! $retval )
                {
                  die('Could not update data: ' . mysql_error());
                }
                else
                    echo 29;
                }

        }

NOTE I'm not seeing any error