摘要:
select employee_id, job_id from employees union all select employee_id, job_id from job_history; select employee_id, job_id from employees union selec 阅读全文
摘要:
内连接:106(106, 11) select e.last_name, d.department_name from employees e, departments d where e.department_id=d.department_id; select e.last_name, d.de 阅读全文