sql，去重查询distinct

[mengfk000]

select DISTINCT `object_id`, t3.width as width, t3.height as height,t3.ismark as ismark, t2.rtime as add_time,t1.add_author as add_author,t1.image_url as image_url,t1.id as id,t1.browse_real_cnt as browse_real_cnt 
from comments as t2 
left join ornamentations as t1 on t1.id = t2.object_id 
left join ornamentation_images as t3 on t3.ornamentation_id = t1.id 
where ( t2.uid = 1013 ) AND ( t1.enable = '0' ) 
ORDER BY t2.id desc LIMIT 0,5 

select后面的条件，带t3正常，能去重复的，加了t2，t1就没法去重复的了

[xuzuning]

DISTINCT 作用于整行 你的3个表中只要存在一对多的情况就难说了

[mengfk000]

引用 1 楼 xuzuning 的回复:

DISTINCT 作用于整行 你的3个表中只要存在一对多的情况就难说了

那该怎么写呢?我刚才也查了，一个表用distinct，多个表的时候就不用它了，我没看懂别人的说法

[xuzuning]

再套一个 select

select DISTINCT * from 
  (`object_id`, t3.width as width, t3.height as height,t3.ismark as ismark, t2.rtime as     add_time,t1.add_author as add_author,t1.image_url as image_url,t1.id as id,t1.browse_real_cnt as   browse_real_cnt 
  from comments as t2 
  left join ornamentations as t1 on t1.id = t2.object_id 
  left join ornamentation_images as t3 on t3.ornamentation_id = t1.id 
  where ( t2.uid = 1013 ) AND ( t1.enable = '0' ) 
  ORDER BY t2.id desc) T
 LIMIT 0,5

[mengfk000]

引用 3 楼 xuzuning 的回复:

再套一个 select

select DISTINCT * from 
  (`object_id`, t3.width as width, t3.height as height,t3.ismark as ismark, t2.rtime as     add_time,t1.add_author as add_author,t1.image_url as image_url,t1.id as id,t1.browse_real_cnt as   browse_real_cnt 
  from comments as t2 
  left join ornamentations as t1 on t1.id = t2.object_id 
  left join ornamentation_images as t3 on t3.ornamentation_id = t1.id 
  where ( t2.uid = 1013 ) AND ( t1.enable = '0' ) 
  ORDER BY t2.id desc) T
 LIMIT 0,5

报错，报 from comments as t2 from错了

[xuzuning]

哦，漏了 select ..... from (select `object_id`, t3.width as....