選擇有兩列

-1

的獨特組合僅排我的影片獲取的結果就像一個SQL查詢：選擇有兩列

[{"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只有獨特的組合。我只需要5行中的2行，因爲只有2行有獨特的組合。像這樣：

[{"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"},

我該如何做到這一點？

來源

2017-04-04 gaurav

兩者有什麼區別？ –

請更新您的查詢 –

1-分組標準是什麼 2-除非您使用像SUM（），MAX（）這樣的集合函數，否則您不能像這樣對列進行分組。3-我確定這個問題已經在這個網站回答 –

添加GROUP BY這樣

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

樣品

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>

來源

2017-04-04 12:50:37

回答

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