使用加入和分组...有错误

SELECT d.DEPARTMENT_NAME 
    FROM Department d, 
     Student s 
    WHERE d.DEPARTMENT_ID = s.DEPARTMENT_ID 
GROUP BY d.DEPARTMENT_NAME 
    HAVING COUNT(s.STUDENT_ID) < MAX(COUNT(s.STUDENT_ID));

该代码用于加入学生和部门表。各部门之间的关键是department_id。需要找到没有最多学生人数的部门。错误是组函数嵌套过深。不允许嵌套到3？使用加入和分组...有错误

这里是确切的错误

ORA-00935：组函数嵌套太深

来源

2017-06-02 Saket Shrivastava

哪个[DBMS]（https://en.wikipedia.org/wiki/DBMS）您使用的？什么是**确切的**错误信息（** [编辑] **你的问题 - 做**不** **邮编或额外的信息在评论中） –

我想你需要使用COUNT代替SUM有部分查询 –

您能否发布您遇到的问题（错误信息）？ – Susang

UPD。哦，史〜！我刚刚提到了与Oracle有关的问题。我不知道它的语法为rank()函数，但我认为它应该非常接近Sql Server。

这就是：

;with Department(DEPARTMENT_ID, DEPARTMENT_NAME) as (
    select 1, 'first' union all 
    select 2, 'second' union all 
    select 3, 'third' 
) 
, Student(STUDENT_ID, DEPARTMENT_ID) as (
    select 1, 1 union all 
    select 2, 2 union all 
    select 3, 2 union all 
    select 4, 2 union all 
    select 5, 3 union all 
    select 6, 3 union all 
    select 7, 3 
) 
, DepOrdered as (
    select 
     d.DEPARTMENT_ID, 
     d.DEPARTMENT_NAME, 
     s.StudentCnt, 
     -- rank departments by the number of students 
     rank() over (order by s.StudentCnt desc) as Rnk 
    from Department d 
    cross apply (
     -- for every department count its students 
     select 
      count(s.STUDENT_ID) StudentCnt 
     from Student s 
     where 
      d.DEPARTMENT_ID = s.DEPARTMENT_ID 
    ) s 
) 
select 
    DEPARTMENT_ID, 
    DEPARTMENT_NAME, 
    StudentCnt 
from DepOrdered 
where 
    -- Rnk = 1 would have all departments with max number of students 
    Rnk > 1

来源

2017-06-02 08:01:24 pkuderov

使用加入和分组...有错误

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