Question

我有3张桌子。用户，PC，部门用户具有DepartmentID和PCID列，其中包含Departments中的ID和用户中的PCID。

我需要从用户拥有最高工资总额的部门中选择pc.id

我对这个问题做了一些尝试。

WITH cte AS (select s.did, max(Sum_Salary) as Sum_Salary from (select d.ID as did ,sum(u.Salary) as Sum_Salary from dbo.users u 
inner join Departments d on u.DepartmentID=d.id 
group by d.ID ) s group by s.did), cte2 as (select cte.did, cte.Sum_Salary as maxx from cte where Sum_Salary=(select max(Sum_Salary) from cte))
select cte2.did,cte2.maxx,pc.id as pc_id from cte2
inner join users u on cte2.did=u.DepartmentID 
inner join PC on u.PCID=PC.id
;

有效。我对更有效的算法感兴趣。

Answer 1

根据你的描述，我使用了两个ctes：第一个用于计算每个组合（部门，用户）的工资总和，第二个用于查找第一个cte中工资的最大总和。然后我加入了两个cte，只挑选那些最高工资额的PCID。

WITH cte AS (
  SELECT d.id, u.PCID, SUM(u.Salary) AS Sum_Salary
  FROM users u JOIN Departments d ON u.DepartmentID = d.id
  GROUP BY d.id, u.PCID
), cte1 AS (
SELECT cte.id AS DeptID, MAX(Sum_Salary) AS Max_Sum_Salary 
FROM cte
GROUP BY cte.id)
SELECT cte1.DeptID, cte.PCID, d.name
FROM cte 
JOIN cte1 ON cte1.DeptID = cte.id AND cte.Sum_Salary=cte1.Max_Sum_Salary
JOIN Departments d ON d.id = cte1.DeptID

Answer 2

您可以在部门内对薪水进行排序，可以返回第一个用户

SELECT * FROM (
    select d.Name as dname,ROW_NUMBER()OVER(PARTITION BY u.DepartmentID ORDER BY u.Salary desc) AS SeqNO
    FROM dbo.users u
    inner join Departments d on u.DepartmentID=d.id
    inner join PC on u.PCID=PC.id
    where u.salary>500 
) AS t WHERE t.SeqNO=1

从列中的多个值中查找最大值

2 个答案: