1、员工关系表和薪水表连接,查询员工薪水相关信息
select a.emp_no,a.dept_no,b.salary as emp_salary from dept_emp as a join salaries as b on a.emp_no=b.emp_no where a.to_date='9999-01-01'2、薪水表与部门表右连接,查询部门经理的薪水
select c.emp_no as manager_no,d.dept_no,.csalary as manager_salary from salaries as c right join dept_manager as d on c.emp_no=d.emp_no where d.to_date='9999-01-01'3、1表和2表左连接,查询员工薪水大于部门经理薪水的信息
select e.emp_no,f.manager_no,e.emp_salary,f.manager_salary from (select a.emp_no,a.dept_no,b.salary as emp_salary from dept_emp as a join salaries as b on a.emp_no=b.emp_no where a.to_date='9999-01-01') as e left join (select c.emp_no as manager_no,d.dept_no,c.salary as manager_salary from salaries as c right join dept_manager as d on c.emp_no=d.emp_no where d.to_date='9999-01-01') as f on e.dept_no=f.dept_no where e.emp_salary>f.manager_salary;