reducing repetitive code in PHP - php

Question

I'm using this same block of code in numerous PHP files and sometimes in the same PHP file (e.g., when there's an if/else. I know there's a better way, but I'm not quite sure how to do it. I want to replace this big block with something, but not sure what fits. require maybe?
$hostname = 'localhost';
$database = 'dev_testing';
$username = 'root';
$password = 'XXXXXX';
$dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

Answer 1

The answers by #maalls and #TahaPaksu are good, but #marcB's comment is even better: usually you'd want to connect to the database only once per script execution. I don't want to kick you right in the direction of dependency injection, but as an intermediate solution, I'd like to suggest this class, which looks roughly like a singleton, but is actually the Memoization pattern implementation (see also PHP Design Patterns for other pattern examples).
Anyway: the code:
class Database() {
static private $connection = null;
public static function getConnection() {
if (static::$connection === null) {
$hostname = 'localhost';
$database = 'dev_testing';
$username = 'root';
$password = 'XXXXXX';
$dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
static::$connection = $dbh;
}
return static::$connection;
}
}
In your script you can call it using
$dbh = Database::getConnection();
You can call that line as often as you like but it will only connect to the database the first time it's called for that script. Subsequent calls will just return the same connection. This will save quite some overhead on your database.

Answer 2

Create a separate file (for ex. "connection.php"), put the code in it, and everywhere you need it, include the following at the begining of your code:
require_once('connection.php');

Answer 3

you can use a global function which you include in top of your php files:
require_once("db.php");
file db.php:
function db_connect(){
$hostname = 'localhost';
$database = 'dev_testing';
$username = 'root';
$password = 'XXXXXX';
$dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
return $dbh;
}
and in your files:
$dbh = db_connect();
...
// don't forget to close db before you open a new connection!
$dbh = null;