union all关联两个不相关的表，按时间排序

表uc_diary与uc_photo是两个完全不相关的表，用union all可以将这里个表的数据关联到一起，使用时间排序，常用于新鲜事的显示，讲日志，相册，说说等动态放到一起，安装时间排序

select diary_id as id,
       diary_title as title,
       diary_text as contentandname,
       post_time,
       'diary' as type 
from 
uc_diary 
where
diary_state='0' AND emp_id='eedc8ae7-be7b-41d6-8887-283804d6aac9'
union all
select photo_id as id,
       (select title from uc_album where album_id=uc.album_id AND album_state='0' and emp_id='eedc8ae7-be7b-41d6-8887-283804d6aac9') as title,
       filename as contentandname,
       post_time,
       'photo' as type 
from 
uc_photo uc
where photo_state='0' and emp_id='eedc8ae7-be7b-41d6-8887-283804d6aac9'
order by post_time desc