php 二维数组根据value值分组

示例

$order_item = Array (  
    0 => Array ( 'order_id' => 1111 ,'item_id' => 1, 'pro_id' => 1, 'pro_name' => 1111 ,'buy_num' => 5),  
    1 => Array ( 'order_id' => 1111 ,'item_id' => 2 ,'pro_id' => 2 ,'pro_name' => 2222, 'buy_num' => 5 ),
    2 => Array ( 'order_id' => 2222 ,'item_id' => 3 ,'pro_id' => 1 ,'pro_name' => 2222, 'buy_num' => 1 ),
    3 => Array ( 'order_id' => 2222 ,'item_id' => 4 ,'pro_id' => 2 ,'pro_name' => 2222, 'buy_num' => 1 )
);

遍历一次数组

$items = array();
foreach ($order_item as $value) {
    $order_id = $value['order_id'];
    unset($value['order_id']);

    if(!isset($items[$order_id])) {
        $items[$order_id] = array('order_id'=>$order_id, 'items'=>array());
    }
    $items[$order_id]['items'][] = $value;

}

遍历两次数组

$items = array();
$res =array();
foreach ($order_item as $value) {
    $items[$value['order_id']]['items'][] = array_slice($value, 1);
}
foreach ($items as $key => $value) {
    $res[] = array('order_id'=>$key,'item'=>$value['items']);
}
unset(<span></span>items);