mysql group by uid哪个uid与另一个查询匹配

我想得到10兰特的结果，这

image！=''，按
uid
分组，这些
uid
与
select uid from user\u table，type='1'
中的相同。但是我的查询只返回2个结果。问题在哪里

select * from article_table where image!='' 
order by rand() 
group by uid 
in (select uid from user_table where type='1') 
limit 10

我会用一个
join
来代替

select *
  from article_table at
  join ( select uid
           from user_table
          where type = '1' ) ut
    on at.uid = ut.uid
 where image != ''
 group by at.uid
 order by rand()
 limit 10

或者，您可能希望限制
user\u表
中的
uid
s的数量，以便更快地开始：

select at.*
  from article_table at
  join ( select uid
           from user_table
          where type = '1'
          order by rand()
          limit 10 ) ut
    on at.uid = ut.uid
 where image != ''
 group by at.uid
 order by rand()
 limit 10

我在这里假设每个用户都有很多文章。尽管看起来更可怕，但内部选择中的
order by rand（）
是在一个较小的数据集之上的，这将加快速度，而外部选择中的
order by
只需处理较少的行数

请小心，按随机值排序可能会导致严重的性能损失，因为您必须遍历与where子句匹配的整个表。有。
我会用一个
连接来代替

select *
  from article_table at
  join ( select uid
           from user_table
          where type = '1' ) ut
    on at.uid = ut.uid
 where image != ''
 group by at.uid
 order by rand()
 limit 10

或者，您可能希望限制
user\u表
中的
uid
s的数量，以便更快地开始：

select at.*
  from article_table at
  join ( select uid
           from user_table
          where type = '1'
          order by rand()
          limit 10 ) ut
    on at.uid = ut.uid
 where image != ''
 group by at.uid
 order by rand()
 limit 10

我在这里假设每个用户都有很多文章。尽管看起来更可怕，但内部选择中的
order by rand（）
是在一个较小的数据集之上的，这将加快速度，而外部选择中的
order by
只需处理较少的行数

请小心，按随机值排序可能会导致严重的性能损失，因为您必须遍历与where子句匹配的整个表。有。
以下查询将完成此操作

SELECT * 
FROM   article_table 
WHERE  image!='' 
       AND uid IN (SELECT DISTINCT uid 
                   FROM   user_table 
                   WHERE  TYPE = '1' 
                   LIMIT  10) 
GROUP  BY uid 
ORDER  BY Rand() 
LIMIT  10 

下面的查询将执行此操作

SELECT * 
FROM   article_table 
WHERE  image!='' 
       AND uid IN (SELECT DISTINCT uid 
                   FROM   user_table 
                   WHERE  TYPE = '1' 
                   LIMIT  10) 
GROUP  BY uid 
ORDER  BY Rand() 
LIMIT  10