Question

I am new to PHP and would like to ask, what will be the best possible way to declare application level variables and database connection strings or configurations?

How are these application level variables accessible to my scripts?

Answer 1

It’s commonplace (at time of writing) to store connection information in constants, in a file named config.php or similar. Due to the sensitive nature of the file’s contents, it’s also a good idea to store this file outside of the web root.

So you would have, in config.php:

<?php
define('DBHOST', 'localhost');
define('DBUSER', 'root');
define('DBPASS', '');
define('DBNAME', 'your_dbname');

And then to use in your scripts:

<?php
require_once('config.php');

$conn = mysql_connect(DBHOST, DBUSER, DBPASS) or die('Could not connect to database server.');
mysql_select_db(DBNAME) or die('Could not select database.');
...

Presuming your config.php is in the same directory as your script.