No lo haga de esa manera, aquí hay una mejor manera, primero, agregue un campo para almacenar en la tabla de usuarios la última ID de cualquier nueva entrada de registro, luego cree un disparador que actualice ese campo en cada nuevo campo insertado, luego ( opcional) cree una vista para tener una "tabla" completa para consultar.
-- Add new field to save the modified id
ALTER TABLE `users` ADD `last_mod_id` INT(11) NOT NULL, ADD INDEX (`last_mod_id`);
-- Drop the trigger just in case it exists
DROP TRIGGER IF EXISTS `update_last_id`;
-- Create a trigger to save the last modified id each time a row is created
DELIMITER ;;
CREATE TRIGGER update_last_id
AFTER INSERT ON user_log
FOR EACH ROW
BEGIN
UPDATE `users`
SET `last_mod_id` = NEW.id
WHERE `id` = NEW.idrel;
END;
;;
-- Emtpy your table
TRUNCATE `user_log`;
-- Create all new registries
INSERT INTO `user_log` VALUES (1,1,'log1','2014-01-01 13:00:00');
INSERT INTO `user_log` VALUES (2,1,'log2','2014-01-02 13:00:00');
INSERT INTO `user_log` VALUES (3,2,'log3','2014-01-03 13:00:00');
INSERT INTO `user_log` VALUES (4,2,'log4','2014-01-04 13:00:00');
INSERT INTO `user_log` VALUES (5,3,'log5','2014-01-05 13:00:00');
INSERT INTO `user_log` VALUES (6,3,'log6','2014-01-06 13:00:00');
-- Query
SELECT
u.id,
u.name,
u.last_mod_id,
l.event,
l.log
FROM
`users` as u
INNER JOIN
`user_log` as l
ON (l.id = u.last_mod_id)
-- Drop view if exists
DROP VIEW IF EXISTS `users_log_view`;
-- View
CREATE VIEW `users_log_view` AS
SELECT
u.id,
u.name,
u.last_mod_id,
l.event,
l.log
FROM
`users` as u
INNER JOIN
`user_log` as l
ON (l.id = u.last_mod_id);
-- Query
SELECT * FROM `users_log_view` WHERE `id` = 1;