Settings.php

<?php
	/**
	 * Provides the installed database schema version from the database (if available)
	 *
	 * Queries the database to get the installed database version number. If not available,
	 * also checks the legacy
	 *
	 * @author Jonathan Davis
	 * @since 1.3
	 *
	 * @param string $legacy Set to anything but boolean false to attempt to lookup the version from the pre-1.2 settings table
	 * @return integer The installed database schema version number (0 means not installed)
	 **/
	public static function dbversion ( $legacy = false ) {

		$source = $legacy ? 'setting' : self::$table;
		$table = DatabaseObject::tablename($source);
		$version = DB::query("SELECT value FROM $table WHERE name='db_version'", 'col');

		// Try again using the legacy table
		if ( false === $version && false === $legacy ) $version = self::dbversion('legacy');

		return (int)$version;
	}