什么是 SQL oracle 查询来找出从雇用日期起的最大经验？

Question

必须找到最有经验的员工。

select empno, ename, 
from emp
where max(months_between(SYSDATE,hiredate))

我的软件在 sysdate 上出现错误，所以任何人都可以验证这是否正确。

Answer 1

您可以使用：

select e.*
from emp e
order by hiredate asc
fetch first 1 row only;

如果您想要重复，请添加 with ties。

以上适用于 Oracle 12C+。在早期版本中，您需要一个子查询：

select e.*
from (select e.*,
             row_number() over (order by hiredate) as seqnum
      from emp e
     ) e
where seqnum = 1;

Answer 2

使用NOT EXISTS:

select e.empno, e.ename 
from emp e
where not exists (select 1 from emp where hiredate < e.hiredate)

或：

select empno, ename 
from emp 
where hiredate = (select min(hiredate) from emp)

或像这样修改查询的 WHERE 子句：

select empno, ename 
from emp 
where months_between(SYSDATE, hiredate) = (
  select max(months_between(SYSDATE, hiredate)) 
  from emp
)

What will be the SQL oracle query for finding out the maximum experience from hire date?