选择有两列

-1

的独特组合仅排我的影片获取的结果就像一个SQL查询：选择有两列

[{"id":89,"sender_id":2,"reciever_id":1,"message":"no reply","deleted_at":null,"created_at":"2017-04-04 17:01:20","updated_at":"2017-04-04 17:01:20"}, 

{"id":88,"sender_id":1,"reciever_id":2,"message":"hiiiii","deleted_at":null,"created_at":"2017-04-04 16:59:47","updated_at":"2017-04-04 16:59:47"}, 

{"id":87,"sender_id":5,"reciever_id":1,"message":"hiiiii","deleted_at":null,"created_at":"2017-04-04 16:59:43","updated_at":"2017-04-04 16:59:43"}, 

{"id":86,"sender_id":1,"reciever_id":5,"message":"hiiii","deleted_at":null,"created_at":"2017-04-04 16:59:38","updated_at":"2017-04-04 16:59:38"}, 

{"id":85,"sender_id":1,"reciever_id":5,"message":"hiii vRUN\n","deleted_at":null,"created_at":"2017-04-04 16:10:51","updated_at":"2017-04-04 16:10:51"}]

但我想的sender_id和reciever_id只有独特的组合。我只需要5行中的2行，因为只有2行有独特的组合。像这样：

[{"id":89,"sender_id":2,"reciever_id":1,"message":"no reply","deleted_at":null,"created_at":"2017-04-04 17:01:20","updated_at":"2017-04-04 17:01:20"}, 

{"id":87,"sender_id":5,"reciever_id":1,"message":"hiiiii","deleted_at":null,"created_at":"2017-04-04 16:59:43","updated_at":"2017-04-04 16:59:43"},

我该如何做到这一点？

来源

2017-04-04 gaurav

两者有什么区别？ –

请更新您的查询 –

1-分组标准是什么 2-除非您使用像SUM（），MAX（）这样的集合函数，否则您不能像这样对列进行分组。3-我确定这个问题已经在这个网站回答 –

添加GROUP BY这样

SELECT * 
FROM yourTable 
GROUP BY SUBSTRING_INDEX(SUBSTRING_INDEX(,',',3),':',-1)

样品

mysql> SELECT SUBSTRING_INDEX(SUBSTRING_INDEX('[{"id":89,"sender_id":2,"reciever_id":1,"message":"no reply","deleted_at":null,"created_at":"2017-04-04 17:01:20","updated_at":"2017-04-04 17:01:20"},' ,',',3),':',-1) as result; 
+--------+ 
| result | 
+--------+ 
| 1  | 
+--------+ 
1 row in set (0,00 sec) 

mysql>

来源

2017-04-04 12:50:37

回答

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