mysql - mysql中使用group by时使用group操作无效

Question

 select a.col_name1,max(b.col_name2) from table_a , table_b b where
 a.candidate_id = 900 and a.col_name1 = b.col_name1 and a.col_name2=
  302885 group by b.candidate_id;

这是查询对我来说工作正常

但是当我使用 max(b.col_name2) 它给出了这个错误1111 invalid use of group function。

select a.col_name1,max(b.col_name2) from table_a , table_b b where
a.candidate_id = 900 and a.col_name1 = b.col_name1 and a.col_name2=
max(b.col_name2)group by b.candidate_id;

我如何max(b.col_name2)使用价值

请帮助我。在此先感谢..

Answer 1

此外，始终使用显式 JOIN 语法...

SELECT a.col_name1
     , MAX(b.col_name2) 
  FROM table_a a
  JOIN table_b b 
    ON b.col_name1 = a.col_name1 
 WHERE a.candidate_id = 900 
 GROUP 
    BY b.candidate_id
HAVING a.col_name2 = MAX(b.col_name2);

Answer 2

仅仅因为您的查询运行并不意味着它“运行良好”。

Mysql 有一些奇怪的分组功能。

尝试这个：

select
  a.col_name1,
  max(b.col_name2)
from table_a
join table_b b
  on a.col_name1 = b.col_name1
where a.candidate_id = 900
and a.col_name1 = b.col_name1
and a.col_name2 = 302885
group by a.col_name1;

更正/改进：

• 格式化
• 连接语法
• 按列分组

Answer 3

尝试这个

   select a.col_name1,max(b.col_name2) 
   from table_a , table_b b 
   where a.candidate_id = 900 
   and a.col_name1 = b.col_name1 
   group by b.candidate_id 
   having a.col_name2= max(b.col_name2)

或者

   select a.col_name1,max(b.col_name2) 
   from table_a , table_b b 
   where a.candidate_id = 900 
   and a.col_name1 = b.col_name1 
   and  a.col_name2 in ( select max(col_name2) from table_b)
   group by b.candidate_id 

Answer 4

使用 Group By 时，需要在 Have 子句中指定组的 where 子句：

select a.col_name1,
  max(b.col_name2) 
from table_a , table_b b 
where a.candidate_id = 900 and 
  a.col_name1 = b.col_name1 
group by b.candidate_id
having a.col_name2 = max(b.col_name2)