为什么我不能用PHP连接到mysql

我是php / mysql的新手，我想简单地连接到我的数据库。当我在我的服务器上运行下面的代码时，我得到一个http 500错误。我在端口80打开的Ubuntu服务器机器（不是虚拟机）上托管它。当然安装了php和mysql服务器。



我尝试过：

I am new to php/mysql and i want to simply connect to my database. When i run the code below on my server i get a http 500 error. I am hosting it on a Ubuntu server machine (not a virtual machine) with port 80 open. of course php and mysql server are installed.

What I have tried:

<?php
	$servername = "localhost";
	$username = "root";
	$password = "*******";


    mysql_connect($servername,$username,$password);
	echo "hi";
?>