Question

in the past I have used smt like:

$con = mysql_connect("localhost", "root", "root") or
die("Could not connect: " . mysql_error());

mysql_select_db("xxx");

But now, I’ve noticed everybody started using smt like this:

if (!defined('DB_HOST')) define('DB_HOST','localhost');
if (!defined('DB_USER')) define('DB_USER','root');
if (!defined('DB_PASS')) define('DB_PASS','root');
if (!defined('DB_NAME')) define('DB_NAME','xxx');

What’s different about their usage? For example echoing, filtering..

Thanks for help

Answer 1

Well, none of them are wrong, it’s your choice. I think the second alternative is more like a good practice. But my statement is valid only if you define it in one file and require_once in the others. Example:

db_config.php:

if (!defined('DB_HOST')) define('DB_HOST','localhost');
if (!defined('DB_USER')) define('DB_USER','root');
if (!defined('DB_PASS')) define('DB_PASS','root');
if (!defined('DB_NAME')) define('DB_NAME','xxx');

query.php:

require_once db_config.php;
$con = mysql_connect(DB_HOST, DB_USER, DB_NAME) or
die("Could not connect: " . mysql_error());
mysql_select_db("xxx");

But why? Imagine that you want to change your database name, user or password. If you have code mysql_connect("localhost", "root", "root") every time you needed it, a change of plans will make you go through a lot of re-coding. But if you define them in one place as the second alternative does, you won’t have to rewrite a lot of files.