登录php / sql工作，但它已被弃用...如何更改？

Question

I have 3 files to login

Can someone look through my code in checklogin... does it look OK. And hwo do I update it so it's not deprecated. mysql_select_db and sql select etc, how can I change the code to update version...

<?php 
$host="localhost"; 
$username="root"; 
$password=""; 
$db_name="members"; 
$tbl_name="user"; 

$username=$_POST['username'];
$password=$_POST['password'];


$con= mysql_connect("localhost","root","","members");
if(!$con)
die("failed to connect");

    mysql_select_db("members",$con);

$sql= "SELECT * FROM user WHERE username='$username' and password='$password'";
$result=mysql_query($sql);

$count=mysql_num_rows($result);

if($count==1)
{
session_start();
$_SESSION['username']=$username; 
header("location:login_success.php");
} 
else {
echo "Wrong Username or Password";
}
?>

Answer 1

Try this code and see if it does what you need. Also, when you post your form are you encrypting your password in anyway? You may need to decrypt the users password so that it matches what is in the DB?

<?php
define('DB_HOSTNAME','localhost');
define('DB_USERNAME','root');
define('DB_PASSWORD','');
define('DB_DATABASE','members');

$username = $_POST['username'];
$password = $_POST['password'];

//CONNECT TO DATABASE
$db = new mysqli(DB_HOSTNAME, DB_USERNAME, DB_PASSWORD, DB_DATABASE);
if($db->connect_errno > 0){
    die('Unable to connect to database [' . $db->connect_error . ']');
}

$userExists = $db->query("SELECT * FROM user WHERE username='{$username}' and password='{$password}'");
$count = count($userExists);

$db->close();

if($count == 1){
    session_start();
    $_SESSION['username'] = $username; 
    header("location:login_success.php");
}else{
    echo "Wrong Username or Password";
}
?>