Development and Production php/MySQL queries management with Mercurial - php

Question

I have a web project I'm versioning with Mercurial and I don't know how to manage access to two different databases; one is for Development purposes and the other one is for Production.
For now my project is still in development, so I access the dev database and make queries on some of its tables with a php script as for example :
<?php
$dbuser = 'something';
$dbpassword = 'something';
$dbname = 'devDBName';
//~ //connect
$link = mysql_connect('servName', $dbuser, $dbpassword);
if (!$link) {
die('Could not connect: ' . mysql_error());
}
metricsName();
function metricsName()
{
$sql = "SELECT id_metric, name_metric FROM metric";
$result = mysql_query($sql); // result set
while($rec = mysql_fetch_array($result, MYSQL_ASSOC)){
$arr[] = $rec;
};
$data = json_encode($arr); //encode the data in json format
echo '({"success": "true", "message" : "OK","data":' . $data . '})';
}
?>
But I don't know how to access a different database for the Production environment, should I make a copy of these PHP scripts and put explicitly the name of the production database? Or is there a way to "parameterize" this?
Any help would be appreciated.

Answer 1

Separate out your code so that the configuration (i.e. database connections, any other environment specific config / code) is kept in one place.
It makes it easier to maintain (as it's kept centrally), and your build / deployment process can deal with which configuration details need to be used.
Clearly your project is at a very early stage, but this approach will help as it grows.

Answer 2

This example is for mysqli, but the idea should apply to the library you are using. in a config.php file do something like:
//define('DB_HOST_NAME', 'prodserver.com');
define('DB_HOST_NAME', "devserver");
define('DB_NAME', "databasename");
define('DB_USER', "username");
define('DB_PW', "password");
you could put some code around the define statements that will check which server the code is running on and determine which database to connect to. If the dev server for the php is different from the prod server for the php.
Then in your database.php do something like
$include_path = $_SERVER['DOCUMENT_ROOT'] . "/someincludedir";
.....
require $include_path . '/config.php';
......
class myDatabase
{
var $db_host_name = DB_HOST_NAME;
var $db_name = DB_NAME;
var $db_user = DB_USER;
var $db_pw = DB_PW;
var $mysqli;
function connect()
{
$this->mysqli = new mysqli
(
$this->db_host_name,
$this->db_user,
$this->db_pw,
$this->db_name
) or die ("mysqli interface failed");
if( mysqli_connect_errno() )
{
printf("COULD NOT CONNECT TO DATABASE -- mysqli connection failed: %s\n", mysqli_connect_error());
}
}
}
Note that the above class assumes it will be a singleton and if you wanted to have multiple connections to the same or different databases you would then parameterize the database, username, etc for the connect function and you could connect to different databases with different objects.