CREATE DATABASE server;
CREATE DATABASE server2;

CREATE TABLE `server`.`accounts` (
`account_id` INT NOT NULL ,
`name` VARCHAR( 64 ) NOT NULL ,
`password` VARCHAR( 64 ) NOT NULL ,
PRIMARY KEY ( `account_id` )
) ENGINE = MYISAM ;

CREATE TABLE `server2`.`accounts` (
`account_id` INT NOT NULL ,
`name` VARCHAR( 64 ) NOT NULL ,
`password` VARCHAR( 64 ) NOT NULL ,
PRIMARY KEY ( `account_id` )
) ENGINE = MYISAM ;

ALTER TABLE server.`accounts` CHANGE `account_id` `account_id` INT( 11 ) NOT NULL AUTO_INCREMENT
ALTER TABLE server2.`accounts` CHANGE `account_id` `account_id` INT( 11 ) NOT NULL AUTO_INCREMENT

INSERT INTO server.accounts (`name`, password) VALUES('admin1', 'password');
INSERT INTO server2.accounts (`name`, password) VALUES('admin2', 'password2');
INSERT INTO server.accounts (`name`, password) VALUES('common', 'password');
INSERT INTO server2.accounts (`name`, password) VALUES('common', 'password');
INSERT INTO server.accounts (`name`, password) VALUES('diffrentpw', '456');
INSERT INTO server2.accounts (`name`, password) VALUES('diffrentpw', '123');

SELECT a . *
FROM (

SELECT *
FROM server.accounts
UNION SELECT *
FROM server2.accounts
) AS a
WHERE `name` = 'common'
AND PASSWORD = 'password'
# RETURNS two ROWS = choose world TO login TO

SELECT a . *
FROM (

SELECT *
FROM server.accounts
UNION SELECT *
FROM server2.accounts
) AS a
WHERE `name` = 'admin1'
AND PASSWORD = 'password'
# RETURNS 1 ON world 1, USE world 1

SELECT *
FROM server.accounts
UNION SELECT *
FROM server2.accounts
) AS a
WHERE `name` = 'diffrentpw'
AND PASSWORD = '123'
# RETURNS 1 ON world 2, USE world 2