Let’s take a look at how to determine whether the login is successful

login.php code is as follows:

<?php
    // 鏈接數(shù)據(jù)庫
    session_start();
    require_once('conn.php');

    //獲取表單的信息
    $name = trim($_POST['username']);
    $password = md5($_POST['password']);
    $_SESSION['username'] = trim($_POST['username']);
    $_SESSION['password'] = trim($_POST['username']);

    //查詢數(shù)據(jù)庫  然后取出數(shù)據(jù)庫的信息，如果和表單提交的信息一致，則登錄成功，進入后臺管理
    $sql = "select * from user where username='$name' and password='$password'";
    $res = mysql_query($sql);
    $row = mysql_fetch_row($res);
    if($row){
        echo "<script>alert('登錄成功')</script>";
        echo "<script>location.href='main.php'</script>";
    }else{
        echo "<script>alert('登錄失敗')</script>";
        echo "<script>history.go(-1);</script>";   //登錄失敗返回上一個頁面
    }
?>

Let’s analyze the above code, open session log.php and submit it to login. php So we get the information submitted by the form in the login.php file

and then store the information into seesion

$_SESSION['username'] = trim($_POST['username'] );
$_SESSION['password'] = trim($_POST['username']);

Note: To save a session, you must first open the session

Link to the database , and then use sql statements to judge the information submitted by the form and the information in the database. If the same user name and password can be found in the database, then the user can log in

If the login is successful, we jump to Backend management page

Login failed, jump to login page