php mysql联合查询与不同的uid

Question

我有一些表还原用户文章。表格的结构就像......

id | uid | imgae |
1  |  1  | 1.jpg |
2  |  1  |       |
3  |  2  | 2.jpg |
4  |  3  | 3.jpg |
5  |  3  |       |
6  |  3  | 4.jpg |
7  |  4  |       |
...

然后我想得到10个结果女巫image!=''

(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)
UNION 
(select * from my_table where image!='' order by rand() limit 1)

以及如何进一步查询。结果是10个不同的uid（a.uid!=b.uid）？代码太长了...任何简单的方法？感谢。

Answer 1

更改限制并按以下方式添加组：

select * from my_table where image!='' order by rand() group by uid limit 10

Answer 2

你为什么不这样做：

SELECT * FROM my_table
WHERE image != ''
ORDER BY RAND()
LIMIT 10

如果你只想要DISTINCT uid，你可以这样做：

SELECT DISTINCT uid, id, image FROM my_table
WHERE image != ''
ORDER BY RAND()
LIMIT 10

（MySQL人刷新我的记忆 - 当你选择DISTINCT uid时，MySQL会选择相应的id，图像行还是更像GROUP BY，你不一定得到相应的行？）< / p>