which db connection

[bbuio]

I've just installed 7.2.9 version but my old project dont works: neither mysql_connect neither pdo..
why?

[Nobbie]

From http://php.net/manual/en/function.mysql-connect.php

Warning

This extension was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0. Instead, the MySQLi or PDO_MySQL extension should be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include:

mysqli_connect()
PDO::__construct()

I case of PDO, youre information is not sufficient for a fix. What exactly is going wrong?