如何在 oracle SQL 中使用 "over(partition by)" 获得第二个最高薪水？

Question

我已经通过查询获得了它：

   SELECT * 
    FROM
      (
      SELECT emp_id,salary,row_number() over(order by salary  desc) AS rk 
      FROM test_qaium
      ) 
    where rk=2;

但是我的一位朋友让我从员工 table 中找到第二 MAX 薪水必须使用 oracle sql 中的“over(partition by )”。任何人都请帮助我。并清除 oracle sql 中“Partition by”的概念。

Answer 1

如果您有多位员工的薪水相同，您的查询将不起作用...

尝试：

SELECT emp_id,
       salary,
       dense_rank() over(order by salary desc) AS rk 
FROM test_qaium

partition by 子句的作用类似于分组依据，这里没有任何需要分组的内容。

Answer 2

Oracle 设置:

CREATE TABLE test_qaium ( emp_id, salary, department_id ) AS
  SELECT  1, 10000, 1 FROM DUAL UNION ALL
  SELECT  2, 20000, 1 FROM DUAL UNION ALL
  SELECT  3, 30000, 1 FROM DUAL UNION ALL
  SELECT  4, 40000, 1 FROM DUAL UNION ALL -- One highest, one 2nd highest
  SELECT  5, 10000, 2 FROM DUAL UNION ALL
  SELECT  6, 20000, 2 FROM DUAL UNION ALL
  SELECT  7, 30000, 2 FROM DUAL UNION ALL
  SELECT  8, 30000, 2 FROM DUAL UNION ALL -- Two highest, one 2nd highest
  SELECT  9, 10000, 3 FROM DUAL UNION ALL
  SELECT 10, 10000, 3 FROM DUAL UNION ALL -- Two highest, no 2nd highest
  SELECT 11, 10000, 4 FROM DUAL UNION ALL -- One highest, no 2nd highest
  SELECT 12, 20000, 5 FROM DUAL UNION ALL
  SELECT 13, 20000, 5 FROM DUAL UNION ALL
  SELECT 14, 30000, 5 FROM DUAL;          -- One highest, Two 2nd highest

查询：

这将获取每个部门薪水第二高的所有行：

SELECT * 
FROM   (
  SELECT t.*,
         DENSE_RANK() OVER (PARTITION BY department_id
                            ORDER BY salary DESC) AS rnk 
  FROM   test_qaium t
) 
WHERE  rnk=2;

输出:

EMP_ID SALARY DEPARTMENT_ID RNK
------ ------ ------------- ---
     3  30000             1   2
     6  20000             2   2
    12  20000             5   2
    13  20000             5   2

如何在 oracle SQL 中使用 "over(partition by)" 获得第二个最高薪水？

How I can get Second max salary using "over(partition by)" in oracle SQL?

sql

oracle

greatest-n-per-group

window-functions