用於查找第二高的SQL

Question

說我有一張僱員表，我在一列中保留僱員的姓名，在另一列中保留僱員的工資。我應該寫什麼SQL來找到繪製第二高薪水的僱員的名字？

Answer 1

您可以嘗試從「Top 2」中選擇，按升序排序，然後選擇「Top 1」，這會給你正確的行。

Answer 2

你可以這樣做：

select * from (select * from Employees order by salary desc limit 2) as A order by salary asc limit 1; 

Answer 3

我會用row_number()：

select e.* 
from (select e.*, row_number() over (order by salary desc) as seqnum 
     from employees e 
    ) e 
where seqnum = 1 

其他人所說的limit/top/rownum方法：

select e.* 
from (select e.* 
     from employees e 
     order by salary desc 
     limit 2 
    ) t 
order by salary 
limit 1 

你可以做偏移量相同的東西：

select e.* 
from employees e 
order by salary desc 
limit 2, 1 

然而，這些都有一個問題，如果你有最高的薪水領帶。第一種方法是容易被取代row_number()與dense_rank()固定：

select e.* 
from (select e.*, dense_rank() over (order by salary desc) as seqnum 
     from employees e 
    ) e 
where seqnum = 1 

而且，另一種方法是：

select e.* 
from employees e 
where e.salary < (select max(salary) from employees) 
order by salary desc 
limit 1 -- or top 1 or rownum = 1 etc.