sql，去重查询distinct-php教程-PHP中文网

sql，去重查询distinct

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发布： 2016-06-23 13:44:48

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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

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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

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回复讨论(解决方案)

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

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

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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

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报错，报
from comments as t2
from错了

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