login.php

<?php
    $conn  = @mysqli_connect("localhost","root","", "library") or die("Can not connect database");
    // mysql_select_db("library",$conn) or die("Can not select database.");

    if(isset($_POST['username'])) $username =  $_POST['username'];
    if(isset($_POST['password'])) $password =  $_POST['password'];

    $query = "select * from ln_user where username = '$username' and pass = '$password'";
    $count = mysqli_query($conn, $query) or die(mysqli_error());

    // $check = mysql_num_fields($count);
    // echo "$check";


    if(mysqli_num_rows($count) == 1)
    {
        echo "<h1>Welcome to my Homepage !</h1>";
        echo "Phu Van Quat";
    }
    else{
        echo "<h2>Sai tên đăng nhập hoặc mật khẩu !</h2>";
    }
    // echo "$username";
    // echo "$password";
    mysqli_close($conn);
?>