题解 | #获取当前薪水第二多的员工#

select e.emp_no, salary, last_name, first_name
from employees as e join salaries as s on e.emp_no = s.emp_no
where salary=(select s1.salary
from salaries as s1 join salaries as s2 on s1.salary <= s2.salary
group by s1.salary
having count(distinct s2.salary) = 2)

排序问题【子查询＋自查询】

子查询：where 中做过滤条件，过滤薪资第二名。

自查询：求薪资第二名的薪资。

新用法：用自查讯算排名，直接套用语法 s1＜= s2，按s1 分组，对分组后的s2进行去重并统计数量，该数量等于s1的排名（降序）。