<?php
$unsorded = array(
    array(
        "name" => "Test",
        "order_id" => 5
    ),
    array(
        "name" => "Test2",
        "order_id" => 1
    ),
    array(
        "name" => "Test3",
        "order_id" => 6
    )
) ;
echo "Plain: <br />";
var_dump($unsorded);

echo "Sorted DESC: <br />";
usort($unsorded,function($a,$b){
  return $a['order_id'] < $b['order_id'];
});
var_dump($unsorded);
echo "Sorted ASC: <br />";
usort($unsorded,function($a,$b){
  return $a['order_id'] > $b['order_id'];
});
var_dump($unsorded);
?>