使用max ,设置变量思路更清晰

# 运行时间:32ms
# 超过98.67%用Mysql提交的代码
select e.emp_no, s.salary, e.last_name, e.first_name 
from employees as e, salaries as s, 
(select @max_salary:=max(salary) from salaries)r,#获取最大的薪资
(select  @second_mins:= max(salary-@max_salary) from salaries
 where salary !=@max_salary
) rr,  #所有薪资减去最大薪资,排除最大薪资后最大的差
(select @second_salary:=@max_salary+@second_mins)rrr #计算出第二薪资
where e.emp_no=s.emp_no and s.salary = @second_salary #根据薪资查询员工以及其他信息