debian - "Call to undefined function mysql_connect()" after upgrade to php-7

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. Alternatives to this function include:

mysqli_connect()

PDO::__construct()

use MySQLi or PDO

$con = mysqli_connect('localhost', 'username', 'password', 'database');

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