思路:先找出倒数第三的hire_date,然后再输出员工信息

SELECT * FROM employees
WHERE hire_date = (
    SELECT hire_date FROM employees
GROUP BY hire_date
    ORDER BY hire_date DESC
LIMIT 2,1
)

Group BY 也可以用Distinct 替代

笔记: LIMIT 2,1 代表 offset (跳过)前两个,LIMIT (只显示)一个结果。