Mysql案例6_求平均薪资的等级最低的部门的部门名称

背景：当前数据库的department表、salgrade表、employee表，数据分别如下：

SQL语句：

SELECT
            t.*,s.grade
FROM
            (
                    SELECT
                            e.departmentid, d.`name`,AVG(salary) avgsal
                    FROM
                            employee e
                    INNER JOIN
                            department d
                    on
                            e.departmentid=d.id
                    GROUP BY
                            e.departmentid,d.`name`  ) t
INNER JOIN
            salgrade s
ON
            t.avgsal BETWEEN s.losal AND s.hisal
WHERE
            grade = (SELECT
                               MIN(t.grade) mingra
                      FROM (
                                                SELECT
                                                    t.*,s.grade
                                                FROM
                                                        (
                                                                    SELECT
                                                                            e.departmentid, d.`name`,AVG(salary) avgsal
                                                                    FROM
                                                                            employee e
                                                                    INNER JOIN
                                                                            department d
                                                                    on
                                                                            e.departmentid=d.id
                                                                    GROUP BY
                                                                            e.departmentid,d.`name`) t
                                                    INNER JOIN
                                                            salgrade s
                                                    ON
                                                            t.avgsal BETWEEN s.losal AND s.hisal) t
                                                )

原文地址：https://www.cnblogs.com/wodexk/p/10703865.html