题解 | 平均工资

方法一
select avg(salary) from salaries join
(select max(salary) maxs,min(salary) mins from salaries where to_date = '9999-01-01')h
where to_date = '9999-01-01' and
salary!= h.maxs and salary!=h.mins
此方法会把相同的多个最高和最低都去除，因此要根据实际业务调整
方法二
SELECT (SUM(salary) - MAX(salary) - MIN(salary)) / (COUNT(1)-2) avg_salary 
FROM salaries where to_date = '9999-01-01';
此方法就可以只去除一个最高和一个最低