SELECT `login_time` FROM `enterlog_24` WHERE `year` = '2009' AND `month` = 2 AND `day` = 24 AND `user_id` ='1'
union all
SELECT `login_time` FROM `enterlog_25` WHERE `year` = '2009' AND `month` = 2 AND `day` = 25 AND `user_id` ='1'
输出上面两个表里面符合查询条件的所有login_time值