PHP接收json，并将接收数据插入数据库

<?php
require ('connect.php'); /* 本例用到的数据： post_array={"order_id":"0022015112305010013","buyer_id":"2","seller_id":"1","all_price":"100.00","json_list":[{"product_id":"3","product_number":"3"},{"product_id":"8","product_number":"2"},{"product_id":"10","product_number":"4"}]} */ $post_array=$_POST['post_array']; //--解析Json，获取对应的变量值 $obj=json_decode($post_array,TRUE); $order_id = $obj['order_id']; $buyer_id = $obj['buyer_id']; $seller_id = $obj['seller_id']; $all_price = $obj['all_price']; $i=0;//循环变量 //--得到Json_list数组长度 $num=count($obj["json_list"]); //--遍历数组，将对应信息添加入数据库 for ($i;$i<$num;$i++) {     $list_product_id[]=$obj["json_list"][$i]["product_id"];     $list_product_number[]=$obj["json_list"][$i]["product_number"];     $insert_order_product_sql="INSERT INTO tbl_order_product (order_id,product_id,product_number) VALUES (?,?,?)";     $result = $sqlconn -> prepare($insert_order_product_sql);     $result -> bind_param("sss", $order_id,$list_product_id[$i],$list_product_number[$i]);     $result->execute(); } //--添加订单信息 $insert_order_sql="INSERT INTO tbl_order (order_id,buyer_id,seller_id,all_price) VALUES (?,?,?,?)"; $result=$sqlconn->prepare($insert_order_sql); $result->bind_param("ssss",$order_id,$buyer_id,$seller_id,$all_price); $result->execute(); $result -> close(); $sqlconn -> close(); ?>