Question

我有一个mysql查询返回所需的数据，但没有返回唯一的行。我怎样才能确保只返回唯一的行？

这是我的查询

SELECT  a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image
FROM followers a
INNER JOIN donors b ON a.user_id = b.user_id
WHERE following = 257

UNION DISTINCT 

SELECT  a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image
FROM followers a
INNER JOIN donors b ON a.following = b.user_id
WHERE a.user_id = 257

返回user_id的多个结果。如何通过user_id确保结果不会翻倍？

我曾经尝过一个小组，但我一定做错了，因为我无法让它发挥作用。

我回来的结果

**follow_id user_id following   donor_id    firstname   lastname**  image
13  224 257 124 Just    A Donor 224.jpg
11  257 224 124 Just    A Donor 224.jpg
9   257 222 116 Dummy   Donor   222.jpg

得到它......只需按照donor_id进行分组

SELECT * FROM 
(SELECT  a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image
FROM followers a
INNER JOIN donors b ON a.user_id = b.user_id
WHERE following = 257 

UNION DISTINCT 

SELECT  a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image
FROM followers a
INNER JOIN donors b ON a.following = b.user_id
WHERE a.user_id = 257 ) AS t
GROUP BY donor_id

Answer 1

SELECT  DISTINCT a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image
FROM followers a
INNER JOIN donors b ON a.user_id = b.user_id
WHERE following = 257

Answer 2

你试过这个吗？

SELECT  a.follow_id, a.user_id, a.following, b.donor_id, b.firstname, b.lastname, b.image 
FROM followers a 
INNER JOIN donors b ON a.user_id = b.user_id 
WHERE following = 257 or a.user_id = 257

如果行在查询的每一半中都不唯一，您也可以尝试使用SELECT DISTINCT。

MySQL联盟的唯一列

2 个答案: