Example from wp_config.php (wordpress config file) that shows different environments

wp_config.php

/** 
 * Production, Staging, Live
 */
define( 'OXO_LOCAL_A',	'/wordpress/' );
define( 'OXO_STAGE',	'some-stage.domain.com' );

if ( substr($_SERVER['REQUEST_URI'], 0, 11) == OXO_LOCAL_A ) 
{
	// DB
	define( 'DB_NAME',	'wordpress' );
	define( 'DB_USER',	'loginlocal' );
	define( 'DB_PASSWORD',	'passlocal' );
	define( 'DB_HOST',	'localhost' );
	// URL Constants
	define( 'WP_SITEURL',	'http://localhost/wordpress' );
	define( 'WP_HOME',	'http://localhost/wordpress' );
	
	define( 'AUTOSAVE_INTERVAL',	3600 ); // autosave 1x per hour
	define( 'EMPTY_TRASH_DAYS',	0 ); // zero days
	define( 'WP_POST_REVISIONS',	false ); // no revisions

	// DEBUG
	#error_reporting( E_ALL );
	define( 'WP_DEBUG',		true );
	define( 'SAVEQUERIES',		true );
	define( 'WP_DEBUG_LOG',		true ); // file: /core_root/wp-content/debug.log
	define( 'WP_DEBUG_DISPLAY', 	false );
	@ini_set( 'display_errors',	0 );
	
	// ALLOW updates without FTP
	define ( 'FS_METHOD', 'direct' );
}
elseif ( $_SERVER['HTTP_HOST'] == OXO_STAGE ) 
{
    define( 'DB_NAME',		'dbnamestage' );
    define( 'DB_USER',		'loginstage' );
    define( 'DB_PASSWORD',	'passstage' );
	define( 'DB_HOST',	'http://example.com' );

	define( 'WP_SITEURL',	'http://example.com' );
	define( 'WP_HOME',	'http://example.com' );
	
	define( 'AUTOSAVE_INTERVAL',	3600 ); // autosave 1x per hour
	define( 'EMPTY_TRASH_DAYS',	0 ); // zero days
	define( 'WP_POST_REVISIONS',	false ); // no revisions

	// DEBUG
	# error_reporting( E_ALL ); // in case we need it
	define( 'WP_DEBUG',		true );
	define( 'SAVEQUERIES',		true );
	define( 'WP_DEBUG_LOG',		true ); // file: /core_root/wp-content/debug.log
	define( 'WP_DEBUG_DISPLAY', 	false );
	@ini_set( 'display_errors', 	0 );

	// Non-public
	mysql_query( 'UPDATE wp_options SET option_value = false WHERE option_name = "blog_public"' );
}
// Catch all assumes you're using DEV 
else 
{
    define( 'DB_NAME',		'dbnamelive' );
    define( 'DB_USER',		'loginlive' );
    define( 'DB_PASSWORD',	'passlive' );
	define( 'DB_HOST',	'http://example.com' );

	define( 'WP_SITEURL',	'http://example.com' );
	define( 'WP_HOME',	'http://example.com' );

	define( 'AUTOSAVE_INTERVAL',	300 ); // autosave 1x per 5 min
	define( 'EMPTY_TRASH_DAYS',	30 ); // 30 days
	define( 'WP_POST_REVISIONS',	5 ); // 5 Revisions per post

	// DEBUG
	# error_reporting(E_ALL); // in case we need it
	define( 'WP_DEBUG', false );

	// Public
	# mysql_query( 'UPDATE wp_options SET option_value = true WHERE option_name = "blog_public"' );
}