Array sort by key

array_sort.php

$data_array = array(
  array(
    'ItemRef' => 20,
    'ClassRef' => 'test1',
    'Hours' =>  20
  ),
  array(
    'ItemRef' => 21,
    'ClassRef' => 'test2',
    'Hours' =>  10
  )
);

// array sort by Hours

usort($data_array, function ($item1, $item2) {
  if ($item1['Hours'] == $item2['Hours']) return 0;
  return $item1['Hours'] < $item2['Hours'] ? -1 : 1;
});