Question

我有三张桌子办公室，经理，工作人员。以下是这些表格的内容。

办公室

     office_id  office_location  office_telephone  office_fax

     100        brisbane         01438263          789
     101        newyork          01457899          978
     102        chicago          01457989          789

管理器

     office_id  manager_id  manager_name  manager_phone

     100        200         wayne         9879664878
     101        201         tom           9745997669     
     102        202         harry         9789979799

员工

     manager_id  staff_id  salary

     200         300       3000
     201         301       4000
     200         302       5000
     200         303       7856
     201         304       4000
     202         305       7856
     202         306       6000

现在，我需要一个查询来显示每个办公室的员工及其经理的总数。

以下是示例输出

    office_id  office_location  manager_id  count(staff_id)

    100        brisbane         200         3
    101        newyork          201         2
    102        chicago          202         2

直到现在我已经尝试过显示manager_id和为他们工作的员工。

     SELECT manager_id,count(staff_id) from staff group by manager_id;

但我无法显示office_id及其位置。有人可以帮帮我吗？

Answer 1

内部查询首先获得每位经理的计数和总工资......然后，按照链条进行操作以获得其他细节

SELECT
      s.manager_id,
      m.manager_name,
      m.manager_phone,
      o.office_location,
      o.office_telephone,
      o.office_fax,
      s.NumOfEmployees,
      s.AllSalary
   from
      ( select s1.manager_id,
               count(*) as NumEmployees,
               SUM( s1.salary ) as AllSalary
            from staff s1
            group by s1.manager_id ) s
         join manager m
            ON m.manager_id = m.manager_id
            join office o
               ON m.office_id = o.office_id

Answer 2

SELECT o.office_id, 
       o.office_location, 
       m.manager_id, 
       count(*) staff_count
  from staff s
 inner join manager m
    on m.manager_id = s.manager_id
 inner join office o
    on o.office_id = m.office_id
 group by o.office_id, 
          o.office_location,
          m.manager_id;

Answer 3

我刚刚创建了您上面提到的表格和数据，如果您只想要输出中提到的列，您可以使用以下内容：

SELECT O.office_id
    ,office_location
    ,M.manager_id
    ,COUNT(staff_id)
FROM Staff S
INNER JOIN Manager M
    ON S.manager_id = M.manager_id
INNER JOIN Office O
    ON O.office_id = M.office_id
GROUP BY M.manager_id
    ,O.office_id
    ,O.office_location

sql select查询难度大

3 个答案: