ขอคำแนะนำเกี่ยวกับการแยกคำใน String ออกมาเป็นคำแบบ array นะครับ

<?php

$record_1 = '1,2,3,4,6,8,9,11,13,23,34,55,57,59';
$record_2 = '1,2,3,4,6,8,9,11,13';
$record_3 = '1,2,3,4,6,8,9,11,13,23,34,55,57,59,67,68,69,87';

$rec1Arr = explode(',' $record_1);
$rec2Arr = explode(',' $record_2);
$rec3Arr = explode(',' $record_3);

$new = array_merge($rec1Arr, $rec2Arr, $rec3Arr);

$result = mysql_query('SELECT * FROM unit WHERE unit_id IN (' . implode(',', $new) . ')');

$unit = array();

while ( $row = mysql_fetch_array($result) )
{
    $unit[$row['unit_id']] = $row['unit_name'];
}

?>

$record_1 = '1,2,3,4,6,8,9,11,13,23,34,55,57,59';
$array = explode(',', $record_1);

foreach ( $array AS $val )
{
 echo $unit[$val];
}