This page is to compare the data we passed from the login page with the data in the database

If it is incorrect, the user will not be allowed to log in

The specific code is as follows

<?php
session_start();
header("Content-type:text/html;charset=utf-8");
$link = mysqli_connect('localhost','root','root','mybbs');//鏈接數(shù)據(jù)庫
mysqli_set_charset($link,'utf8'); //設(shè)定字符集
$username=$_POST['username'];
$password=md5($_POST['password']);
    if($username==''){
        echo "<script>console.log('請輸入用戶名');location='" . $_SERVER['HTTP_REFERER'] . "'</script>";
        exit;
    }
    if($password==''){
        echo "<script>console.log('請輸入密碼');location='" . $_SERVER['HTTP_REFERER'] . "'</script>";
        exit;
    }
$sql="select id,username,password from member where username= $username";      //從數(shù)據(jù)庫查詢信息
$que=mysqli_query($link,$sql);
$row=mysqli_fetch_array($que);
if($row){
    if($password !=($row['password']) || $username !=$row['username']){
        echo "<script>console.log('密碼錯誤，請重新輸入');location='login.html'</script>";
        exit;
    }
    else{
        $_SESSION['username']=$row['username'];
        $_SESSION['id']=$row['id'];
        echo "<script>console.log('登錄成功');location='index.php'</script>";
    }
}else{
    echo "<script>console.log('您輸入的用戶名不存在');location='login.html'</script>";
    exit;
};
?>

Because we have not registered yet, we cannot log in. Let’s create our registration page