//提交订单    function add_order(){        session_start();        // var_dump($_SESSION);        // die();        // session_destroy();        // die();                   $ary =$_POST['order'];        $ary= json_decode($ary, true);        // var_dump($data1);        // die();                $shop_list = $ary['order'];        $total_money = $ary['order_money'];        $obj =UserModel::getInstance();        //获得user_id            $user_id = $_SESSION['uid'];            //获得对应的cart_id            $sql = "select id from cart where user_id = '$user_id'";            $cart_id = $obj->getOne($sql);                    // $arr = $_SESSION['gwc'];        foreach($shop_list as $k=> $shop){            // var_dump($k);            // die();            // 获取对应商品的订单金额            $xiaoji = $ary[$k];                        // 获取8位随机值作为order_id                $strs="QWERTYUIOPASDFGHJKLZXCVBNM1234567890qwertyuiopasdfghjklzxcvbnm"; $random=substr(str_shuffle($strs),mt_rand(0,strlen($strs)-11),8);            $order_id = strval(time())."$random";            //插入一条订单            $sql = "INSERT INTO orders(id,user_id,xiaoji) VALUES ('$order_id', '$user_id',$xiaoji)";            $obj->exec($sql);            // die();            // echo "$sql";            // die();            foreach($shop as $sid=> $sku_id){                            // 拼接sku_id                // $sku_id = "$goods_id"."_"."$color_id"."_"."$size_id";                $number ="num_$sku_id";                $price = "price_$sku_id";                $num = $ary[$number];                $pay_price = $ary[$price];                //插入一条sku_orders记录                $sql = "INSERT INTO orders_sku(sku_id,orders_id,num,pay_price) VALUES ('$sku_id','$order_id',$num,$pay_price)";                // echo("$sql");                // die();                $obj->exec($sql);                                // $sql = "select count(*) from cart_sku";                // echo("$sql");                // die();                // $_SESSION["goods_number"] = $obj->getOne($sql);                $_SESSION["goods_number"]--;                                                $sql = "delete from cart_sku where sku_id = '$sku_id' and cart_id = '$cart_id'";                // echo("$sql");                // die();                $obj->exec($sql);                            }        }                    echo "OK";        exit;                // die();            }

json_decode($ary, true);这句是把ajax方式传过来的json串，转为php的数组数组形式，还有一种是转为对象。

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$strs="QWERTYUIOPASDFGHJKLZXCVBNM1234567890qwertyuiopasdfghjklzxcvbnm";

$random=substr(str_shuffle($strs),mt_rand(0,strlen($strs)-11),8);

上面两句是从str字符串（包含大小写和数字）获取一个8位的随机值。

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$order_id = strval(time())."$random";这句是使用时间戳和一个随机值拼接形成订单的id。