与2个连接表查询结果一起使用的MySQL组concat重复

Question

我已经加入了2个表并使用组concat来获取某些彩色数据。下面是我的查询。这返回相同的行两次

SELECT GROUP_CONCAT( vehicles.role ORDER BY vehicles.id ASC SEPARATOR '\n') as role,GROUP_CONCAT( vehicles.size ORDER BY vehicles.id ASC SEPARATOR '\n') as size,festivals.id,festivals.ref_no as ref_no, festivals.camping,festivals.tour_mgr_name,festivals.email,festivals.mobile,festivals.name_address, GROUP_CONCAT(namedesgs.name ORDER BY namedesgs.id ASC SEPARATOR '\n') as names,GROUP_CONCAT(namedesgs.designation ORDER BY namedesgs.id ASC SEPARATOR '\n') as designations 
FROM festivals 
    LEFT JOIN namedesgs ON festivals.id = namedesgs.festival 
    LEFT JOIN vehicles ON festivals.id = vehicles.festival 
Group BY festivals.id 

请教如何获取没有重复的数据？

当我用concat的DISTINCT。它不为以下

前工作：

namedesg数据

车辆数据

电流输出

但是在我输出的维基数据上重复了3次，即使有一个数据存在。

这里查询我试图

SELECT t.id, GROUP_CONCAT(a.name SEPARATOR '\n') as name, 
GROUP_CONCAT(a.designation SEPARATOR '\n') as desg ,GROUP_CONCAT(b.role SEPARATOR '\n') as role, 
GROUP_CONCAT(b.size SEPARATOR '\n') as size 
FROM festivals t 
LEFT JOIN namedesgs a ON a.festival=t.id 
LEFT JOIN vehicles b ON b.festival=t.id 
where t.id=4 
GROUP BY t.id 


festivals 

id ref_no 
1 AAA 
2 BBB 
3 CCC 

namedesgs 

id name designation festival(festival table id) 
1 ann SE    1 
2 ben AE    1 
3 Jan cook   1 
4 alun cook   1 
5 hej hik   2 
6 nij AE    1 

vehicles 

id role size festival(festival table id) 
1 r1 14    1 
2 r1 12    1 
3 r2 12    1 
4 r3 12    1 
5 r4 12   2 

我想作为了说就是

festivalid name designations role size 
1   ann SE   r1 14 
      ben AE   r1 12 
      jan cook   r2 12 
      alun cook  r3 12 
      aij AE   
2   hej hik   r4 12 

Answer 1

你想要的东西，你不能把name和designation，并role和size，在结果中有单独的列。在使用GROUP_CONCAT之前，您需要将它们连接起来。并使用DISTINCT删除重复项。

SELECT t.id AS festivalid, 
     GROUP_CONCAT(DISTINCT CONCAT(a.name, ' ', a.designation) SEPARATOR '\n') AS `name designations`, 
     GROUP_CONCAT(DISTINCT CONCAT(b.role, ' ', b.size) SEPARATOR '\n') AS `role size` 
FROM festivals AS t 
LEFT JOIN namedesgs a ON a.festival=t.id 
LEFT JOIN vehicles b ON b.festival=t.id 
GROUP BY t.id