how to fix this?
(I just started using the platform, please do not report.)

error;

Fatal error: Uncaught Error: Call to undefined function mysql_connect() in C:\xampp\htdocs\myproject\assets\connection.php:8 Stack trace: #0 C:\xampp\htdocs\myproject\login.php(3): require_once() #1 {main} thrown in C:\xampp\htdocs\myproject\assets\connection.php on line 8

my login.php

<?php

require_once 'assets/connection.php';
session_start();

?>

my connection.php

<?php

$host = "localhost";
$username = "root";
$pass = "";
$database = "testbase";

$connection = @ mysql_connect($host,$username,$pass,$database) or die("MySql  Yöneticiyle iletişime geçin.");
mysql_select_db($database, $connection) or die("MySql Bağlantısı öneticiyle İletişime geçin.");

?>

>Solution :

The mysql_connect function has been discontinued in the PHP 7.

Use mysqli_connect()

How can create query with mysqli:

$link = mysqli_connect("host", "user", "pass", "database");
mysqli_query($link, $query);

You use PHP 7, correct?