Question

使用SCOTT Schema。我想让薪水最接近平均水平的人。

SELECT sal
      FROM (  SELECT sal
                FROM emp
            ORDER BY ABS ( (SELECT AVG (SAL) FROM EMP) - sal))
     WHERE ROWNUM = 1;

上述解决方案能否得到改善？

Answer 1

with av as (select avg(sal) avgsal from scott.emp)
select emp.*, abs(emp.sal-av.avgsal) dist 
  from scott.emp, av 
  order by dist;

上面看起来对我来说更好，但可能你可以通过分析功能获得最佳效果。类似的东西：

select * from (
  select emp.*, abs(avg(emp.sal) over () - sal) diff 
    from scott.emp order by diff) 
where rownum = 1;

Answer 2

使用子查询拉回员工数据：

select empno, sal, SalDif
from 
  (
    select empno, sal, abs(sal - (select avg(sal) from emp)) as SalDif
    from emp
    order by SalDif
  )
where rownum = 1;

或作为CTE：

with CTE as
  (
    select empno, sal, abs(sal - (select avg(sal) from emp)) as SalDif
    from emp
    order by SalDif
  )
select empno, sal, SalDif
from CTE
where rownum = 1;

Answer 3

您使用的是非标准Oracle功能。子查询中的数据最初没有订单，但在Oracle中您可以对其进行订购，以便以后能够应用ROWNUM标准。 ROWNUM也是Oracle特有的。

此外，可能有几名员工薪水相同，您可以随意挑选其中一名，而不是全部展示。

以下是如何在标准SQL中选择薪酬最接近avarage的员工：

select *
from emp
order by abs(sal - avg(sal) over())
fetch first row with ties;

最后一行仅适用于Oracle 12c。

在旧版本（即Oracle 9i，10i或11g）中，您可以改为对行进行排名：

select empno, ename, sal
from
(
  select empno, ename, sal, rank() over (order by diff) as rnk
  from
  (
    select emp.*, abs(sal - avg(sal) over()) as diff
    from emp
  ) evaluated
) ranked
where rnk = 1;

查询Oracle SCOTT架构 - 哪个薪水最接近平均值？

3 个答案: