找到第N个最高工资

Question

编写SQL查询以从Employee表中获得第n个最高薪水(SQL Server)

| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |

对于此示例,n = 2的第n个最高薪水是200.如果没有第n个最高薪水,则查询应返回null.

| getNthHighestSalary(2) |
+------------------------+
| 200                    |

除了使用函数之外,有没有办法编写这个查询？

Answer 1

另一种可能的方法是使用ROW_NUMBER()或DENSE_RANK()函数.重要的是要知道在第N个职位或之前是否可以有多于一个薪水.

CREATE TABLE #Salary (
    [id] int,
    [salary] numeric(10, 2)
)

INSERT #Salary 
    ([id], [salary])
VALUES
    (1, 100),
    (2, 500),
    (3, 200),
    (4, 300),
    (5, 200);

DECLARE @Position int = 2;

-- With possible duplicate salaries
WITH cte AS (
    SELECT 
        [id], [salary],
        DENSE_RANK() OVER (ORDER BY [salary] ASC) AS [DRPosition]
    FROM #Salary
)
SELECT [id]
FROM cte
WHERE [DRPosition] = @Position
ORDER BY [DRPosition];

-- Without possible duplicate salaries
WITH cte AS (
    SELECT 
        [id], [salary],
        ROW_NUMBER() OVER (ORDER BY [salary] ASC) AS [RPosition]
    FROM #Salary
)
SELECT [id]
FROM cte
WHERE [RPosition] = @Position
ORDER BY [RPosition]

Answer 2

以下内容几乎完全符合您的要求：

select salary
from employee
order by salary desc
offset <n> rows fetch next 1 row only;

NULL唯一的问题是，没有这个薪水的时候，是不返回的。您可以使用子查询来处理：

select (select salary
        from employee
        order by salary desc
        offset <n> rows fetch next 1 row only
       ) as salary;

如果您希望关系具有相同的排名，请select distinct salary在子查询中使用。