sql关联查询—将一个表的查询结果作为新表进行查询操作

SELECT MAX(salary) AS max_salary,e.`department_id`  did
        FROM employees e
        GROUP BY e.`department_id`

SELECT MIN(max_salary),did
FROM
(SELECT MAX(salary) AS max_salary,e.`department_id`  did
        FROM employees e
        GROUP BY e.`department_id`)AS tmp

ELECT MIN(e2.salary)
FROM employees e2
WHERE e2.department_id =
    (SELECT e1.department_id
    FROM employees e1
    GROUP BY e1.department_id
    HAVING MAX(e1.salary) =
        (SELECT MIN(tmp.max_salary) AS min_salary
        FROM(
            SELECT MAX(salary) AS max_salary,e.`department_id`  did
            FROM employees e
            GROUP BY e.`department_id`
            )AS tmp
    )
)

SELECT e1.salary
FROM employees e1,
(SELECT MAX(salary) AS max_salary,e.`department_id`  did
        FROM employees e
        GROUP BY e.`department_id`
        ORDER BY max_salary
        LIMIT 0,1
)AS temp
WHERE e1.department_id = temp.did