update语句中使用子查询

55. 更改 108 员工的信息: 使其工资变为所在部门中的最高工资, job 变为公司中平均工资最低的 job

1). 搭建骨架

update employees set salary = (

), job_id = (


) where employee_id = 108;

2). 所在部门中的最高工资

select max(salary)
from employees
where department_id = (
select department_id
from employees
where employee_id = 108
)

3). 公司中平均工资最低的 job

select job_id
from employees
group by job_id
having avg(salary) =  (
select min(avg(salary))
from employees
group by job_id
)

4). 填充

update employees e set salary = (
select max(salary)
from employees
where department_id = e.department_id
), job_id = (
select job_id
from employees
group by job_id
having avg(salary) =  (
select min(avg(salary))
from employees
group by job_id
)
) where employee_id = 108;

56. 删除 108 号员工所在部门中工资最低的那个员工.
1). 查询 108 员工所在的部门 id

select department_id
from employees 
where employee_id = 108;

2). 查询 1) 部门中的最低工资

select min(salary)
from employees
where department_id = (
select department_id
from employees 
where employee_id = 108;
)

3). 删除 1) 部门中工资为 2) 的员工信息

delete from employees where salary = (
select min(salary)
from employees
where department_id = (
select department_id
from employees 
where employee_id = 108
)
) and department_id = (
select department_id
from employees 
where employee_id = 108
)