[feature/migrations] Basic migrations with schema and data changes

The migrator takes care of applying migrations as necessary.

RFC: http://area51.phpbb.com/phpBB/viewtopic.php?f=84&t=41337

PHPBB3-9737

phpBB/includes/db/migration.php

@@ -0,0 +1,79 @@
+<?php
+/**
+*
+* @package db
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Abstract base class for database migrations
+*
+* Each migration consists of a set of schema and data changes to be implemented
+* in a subclass. This class provides various utility methods to simplify editing
+* a phpBB.
+*
+* @package db
+*/
+class phpbb_db_migration
+{
+	var $db;
+	var $db_tools;
+
+	/**
+	* Migration constructor
+	*
+	* @param dbal			$db			Connected database abstraction instance
+	* @param phpbb_db_tools	$db_tools	Instance of db schema manipulation tools
+	*/
+	function phpbb_db_migration(&$db, &$db_tools)
+	{
+		$this->db = &$db;
+		$this->db_tools = &$db_tools;
+	}
+
+	/**
+	* Defines other migrationsto be applied first (abstract method)
+	*
+	* @return array An array of migration class names
+	*/
+	function depends_on()
+	{
+		return array();
+	}
+
+	/**
+	* Updates the database schema
+	*
+	* @return null
+	*/
+	function update_schema()
+	{
+	}
+
+	/**
+	* Updates data
+	*
+	* @return null
+	*/
+	function update_data()
+	{
+	}
+
+	/**
+	* Adds a column to a database table
+	*/
+	function db_column_add($table_name, $column_name, $column_data)
+	{
+		$this->db_tools->sql_column_add($table_name, $column_name, $column_data);
+	}
+}