题解 | #平均工资#

# 题目：查找排除在职(to_date = '9999-01-01' )员工的最大、最小salary之后，
# 其他的在职员工的平均工资avg_salary。
# 解析：本题考查了avg(column_name)取平均数的用法，随后通过子查询用NOT IN 排除掉题目要求的条件；
SELECT avg(salary) AS avg_salary
FROM salaries
WHERE to_date = "9999-01-01"
AND salary NOT IN (SELECT MAX(salary) FROM salaries WHERE to_date = "9999-01-01")
AND salary NOT IN (SELECT MIN(salary) FROM salaries WHERE to_date = "9999-01-01")