Login function: Let’s first look at the following html code
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>欢迎登录</title>
<style type="text/css">
*{margin: 0px;padding: 0px;}
body{background:#eee;}
#div{width:300px;height:400px;background:#B1FEF9;margin:0 auto;margin-top:150px;
border-radius:20px;}
h3{margin-left:48px;padding-top:60px;}
h4{margin-left:120px;padding-top:60px;font-size: 18px;}
#cnt{width:280px;height:370px;margin-left:33px;padding-top:60px;}
.sub{width:70px;height:30px;border:1px solid #fff;background:#eee;
margin-left:28px;margin-top:20px;}
.sub1{
width:70px;height:30px;border:1px solid #fff;background:#eee;margin-left:150px;margin-top:20px;}
</style>
</head>
<body>
<div id="div">
<h3>欢迎登陆后台管理系统</h3>
<div id="cnt">
<form method="post" action="main.php">
用户名：<input type="text" placeholder="请输入用户名" name="username">
<br><br>
密 码：<input type="password" placeholder="请输入密码" name="password">
<br><br>
<input type="submit" value="登录" class="sub">
</form>
</div>
</div>
</body>
</html>The form is submitted to main.php. Now let’s analyze main.php
After we log in, if we have a lot of There is no web page to operate on for a long period of time. When you operate again, you need to log in. This will use our session knowledge
First we need to open the session
session_start();
Then we need to introduce the file conn.php that links to the database.
require_once('conn.php');
Get the form information, and then save the form information Enter session
$name = $_POST['username'];
$pwd = md5($_POST['password']);
$_SESSION['name']=$name;
$_SESSION['pwd']=$pwd;
Let’s go to the database to query. If there is information submitted by the form in the database, then we should make the information submitted by the form available for login operations
$sql = "select * from user where username='$name' and password='$pwd'";
$info = mysql_query($sql);
$row = mysql_fetch_row($info );
Then judge $row, if it exists, the login is successful, jump to the homepage to add a message, otherwise, return to the page and log in again
if($row) {
echo " alert('Login failed')</script>";
echo "<script>location.href='login.php';</script>"; //Login failed, jump to another one Page
}
<?php
session_start();
require_once('conn.php');
$name = $_POST['username'];
$pwd = md5($_POST['password']);
$_SESSION['name']=$name;
$_SESSION['pwd']=$pwd;
$sql = "select * from user where username='$name' and password='$pwd'";
$info = mysql_query($sql);
$row = mysql_fetch_row($info);
if($row){
echo "<script>alert('登录成功');location.href='message.php';</script>";
}else{
echo "<script>alert('登录失败')</script>";
echo "<script>location.href='login.php';</script>"; //登录失败，跳转到另外一个页面
}
?>