php - MySQL：如何减去更新

Question

我需要减去一个 mysql 更新。这是代码：

<?php
session_start();
//=============Configuring Server and Database=======
$host        =    'localhost';
$user        =    'root';
$password    =    '';
//=============Data Base Information=================
$database    =    'login';

$conn        =    mysql_connect($host,$user,$password) or die('Server Information is not Correct'); //Establish Connection with Server
mysql_select_db($database,$conn) or die('Database Information is not correct');

//===============End Server Configuration============

//=============Starting Registration Script==========


$username    =    mysql_real_escape_string($_POST['txtusername']);

//=============To Encrypt Password===================

//============New Variable of Password is Now with an Encrypted Value========


$insert = "UPDATE `users` SET `points` = (`points`-5) WHERE `username` = '".$username."'";
$insert = "UPDATE `users` SET `lodd` = (`lodd` +1) WHERE `username` = '".$username."'";

 mysql_query($insert); 


header('location: succes.php');
?>

+1 工作完美，但对 -5 不起作用......我该怎么做才能让他们得到 -5 分？

Answer 1

工作正常，+1因为查询-5永远不会被调用，因为它被具有的查询覆盖+1。

你应该有这个代码，（虽然这不是正确的）

$insert = "UPDATE `users` SET `points` = (`points`-5) WHERE `username` = '".$username."'";
mysql_query($insert);

// other codes

$insert = "UPDATE `users` SET `lodd` = (`lodd` +1) WHERE `username` = '".$username."'";
mysql_query($insert); 

后续问题：两列的数据类型是什么？他们是未签名的还是签名的？

Answer 2

您正在用第二个语句覆盖第一个语句。尝试这个：

$insert = "UPDATE `users` SET `points` = (`points`-5), `lodd` = (`lodd` +1) WHERE `username` = '".$username."'";
mysql_query($insert);