结果第一列给出员工的emp_no,
第二列给出其manager的manager_no,
第三列给出该员工当前的薪水emp_salary,
第四列给该员工对应的manager当前的薪水manager_salary
CREATE TABLE dept_emp
(
emp_no
int(11) NOT NULL,
dept_no
char(4) NOT NULL,
from_date
date NOT NULL,
to_date
date NOT NULL,
PRIMARY KEY (emp_no
,dept_no
));
CREATE TABLE dept_manager
(
dept_no
char(4) NOT NULL,
emp_no
int(11) NOT NULL,
from_date
date NOT NULL,
to_date
date NOT NULL,
PRIMARY KEY (emp_no
,dept_no
));
CREATE TABLE salaries
(
emp_no
int(11) NOT NULL,
salary
int(11) NOT NULL,
from_date
date NOT NULL,
to_date
date NOT NULL,
PRIMARY KEY (emp_no
,from_date
));
答案:
select de.emp_no emp_no,dm.emp_no manager_no,de.salary emp_salary,dm.salary manager_salary from
(dept_emp e inner join salaries s on e.emp_no=s.emp_no and s.to_date='9999-01-01') de,
(dept_manager m inner join salaries s on m.emp_no=s.emp_no and s.to_date='9999-01-01') dm
where de.dept_no=dm.dept_no and de.salary > dm.salary
思路:
1、inner join 表1、表3作为de(employees)
2、inner join 表2、表3作为dm(manager)
3、比较dept_no相同下的salary大小