improvement for flexible array_multisort?

[mrhappiness]

function multisort($array, $criterias)
{
  $sort_rule = '';
  foreach($criterias as $criteria)
  {
    foreach($array as $row)
      $sort_array[$criteria['col']][] = $row[$criteria['col']];
    $sort_rule .= '$sort_array['.
     (is_numeric($criteria['col']) ? $criteria['col'] : "'".$criteria['col']."'").
     '], '.$criteria['dir'].',';
  }
  eval("array_multisort($sort_rule".' $array);');
  return $array;
}

$to_sort = array(
    array(
        'column1' => 1,
        'column2' => 4,
        'column3' => 5,
        2
    ),
    array(
        'column1' => 2,
        'column2' => 4,
        'column3' => 6,
        7
    ),
    array(
        'column1' => 2,
        'column2' => 3,
        'column3' => 7,
        17
    ),
    array(
        'column1' => 1,
        'column2' => 3,
        'column3' => 8,
        12
    )
);

$order = array(
    array('col' => 'column1', 'dir' => SORT_ASC),
    array('col' => 'column2', 'dir' => SORT_DESC),
    array('col' => 0, 'dir' => SORT_ASC)
);

print_r($to_sort);
print_r(multisort($to_sort, $order));

i have a very very very large result from a database query so i don't want to select all the data everytime and do the sorting with ORDER BY

do you see something i could change/optimize (beside error handling in multisort() 😉?