array_multisort
便利だったので。
$sort_array = array(
[0] => array(
'id' => 1,
'date' => '20110601',
),
[1] => array(
...
)
)
$param1 = array();
$param2 = array();
foreach($sort_array as $key => $value){
$param1[$key] = $value['id'];
$param2[$key] = $value['date'];
}
array_multisort($param1,SORT_ASC, SORT_NUMERIC,$param2,SORT_DESC, SORT_STRING , $sort_array);