mysql子查询习题98

 #1.查询工资最低的员工信息：last name, salary
 SELECT
     last_name,
     salary
 FROM
     employees
 WHERE
     salary = (
         SELECT
             MIN(salary)
         FROM
             employees
     );

 #2.查询平均工资最低的部门信息
 SELECT
     *
 FROM
     departments
 WHERE
     department_id = (
         SELECT
             department_id
         FROM
             employees
         GROUP BY
             department_id
         ORDER BY
             avg(salary)
         LIMIT 1
     );

 #3.查询平均工资最低的部门信息和该部门的平均工资
 #①各部门的平均工资
 SELECT
     avg(salary),
     department_id
 FROM
     employees
 GROUP BY
     department_id #②求出最低平均工资的部门编号
     SELECT
         avg(salary),
         department_id
     FROM
         employees
     GROUP BY
         department_id
     ORDER BY
         avg(salary)
     LIMIT 1;

 #③查询部门信息
 SELECT
     d.*, ag
 FROM
     departments d
 JOIN (
     SELECT
         avg(salary),
         department_id
     FROM
         employees
     GROUP BY
         department_id
     ORDER BY
         avg(salary)
     LIMIT 1
 ) ag_dep ON d.department_id = ag_dep.department_id #4.查询平均工资最高的job信息
 SELECT
     avg(salary)
 FROM
     employees
 GROUP BY
     job_id
 ORDER BY
     avg(salary) DESC
 LIMIT 1 ②查询job信息 SELECT
     *
 FROM
     jobs
 WHERE
     job_id = (
         SELECT
             job_id
         FROM
             employees
         GROUP BY
             job_id
         ORDER BY
             avg(salary) DESC
         LIMIT 1
     );

 #5.查询平均工资高于公司平均工资的部门有哪些？
 SELECT
     avg(salary),
     department_id
 FROM
     employees
 GROUP BY
     department_id;

 HAVING
     avg(salary) > (
         SELECT
             avg(salary)
         FROM
             employees
     );

 #6.查询出公司中所有 manager的详细信息
 SELECT
     *
 FROM
     employees
 WHERE
     employee_id IN (
         SELECT DISTINCT
             manager_id
         FROM
             employees
     );

 #7.各个部门中最高工资中最低的那个部门的最低工资是多少
 SELECT
     min(salary),
     department_id
 FROM
     employees
 WHERE
     department_id = (
         SELECT
             department_id
         FROM
             employees
         GROUP BY
             department_id
         ORDER BY
             max(salary)
         LIMIT 1
     );

 #8.查询平均工资最高的部门的 manager的详细信息：last_name, department id, email
 SELECT
     last_name,
     d.department_id,
     email,
     salary
 FROM
     employees e
 JOIN departments d ON d.manager_id = e.manager_id
 WHERE
     d.department_id = (
         SELECT
             department_id
         FROM
             employees
         GROUP BY
             department_id
         ORDER BY
             avg(salary) DESC
         LIMIT 1
     );