微微工作室

$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 )
);

$ar = array();
$result = array();
foreach($order_item as $k => $v) {
   $ar[$v['order_id']]['items'][] = array_slice($v, 1);
}
foreach($ar as $k => $v) $result[] = array('order_id' => $k, 'items' => $v['items']);

echo '<pre style="font:10px Tahoma;">';
print_r($result);

/*
Array
(
    [0] => Array
        (
            [order_id] => 1111
            [items] => Array
                (
                    [0] => Array
                        (
                            [item_id] => 1
                            [pro_id] => 1
                            [pro_name] => 1111
                            [buy_num] => 5
                        )

                    [1] => Array
                        (
                            [item_id] => 2
                            [pro_id] => 2
                            [pro_name] => 2222
                            [buy_num] => 5
                        )

                )

        )

    [1] => Array
        (
            [order_id] => 2222
            [items] => Array
                (
                    [0] => Array
                        (
                            [item_id] => 3
                            [pro_id] => 1
                            [pro_name] => 2222
                            [buy_num] => 1
                        )

                    [1] => Array
                        (
                            [item_id] => 4
                            [pro_id] => 2
                            [pro_name] => 2222
                            [buy_num] => 1
                        )

                )

        )

)
*/

不同思路的解决方案

<?php

$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 )
);

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

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

    $items[$order_id]['items'][] = $item;
}
// 下面这一步可不要
sort($items);
print_r($items);

$arr = array(
	array('countyid' => 1, 'county' => '中国','province'=>'湖南'),
	array('countyid' => 1, 'county' => '中国','province'=>'湖南'),
	array('countyid' => 3, 'county' => '日本','province'=>'名古屋'),
	array('countyid' => 3, 'county' => '日本','province'=>'东京'),
	array('countyid' => 1, 'county' => '中国','province'=>'北京'),
	array('countyid' => 1, 'county' => '中国','province'=>'山东'),
	array('countyid' => 1, 'county' => '中国','province'=>'山东'),
	array('countyid' => 2, 'county' => '美国','province'=>'安大略'),
	array('countyid' => 2, 'county' => '美国','province'=>'安大略'),
	array('countyid' => 3, 'county' => '日本','province'=>'名古屋'),
);
foreach($arr as $v){
	$c[$v['county']]++;
	$cp[$v['county'].' '.$v['province']]++;
}
var_dump($c);
var_dump($cp);
输出：
 <pre>array(3) {
  ["中国"] => int(5)
  ["日本"] => int(3)
  ["美国"] => int(2)
}</pre><pre>array(6) {
  ["中国 湖南"] => int(2)
  ["日本 名古屋"] => int(2)
  ["日本 东京"] => int(1)
  ["中国 北京"] => int(1)
  ["中国 山东"] => int(2)
  ["美国 安大略"] => int(2)
}</pre>