[打卡]自连接

SELECT e.employee_id,e.last_name,d.department_name,l.city 
from employees e,departments d,locations l 
WHERE e.department_id=d.department_id and d.location_id=l.location_id;
SELECT * FROM job_grades;
SELECT e.last_name,e.salary,j.grade_level
from employees e,job_grades j
WHERE e.salary BETWEEN j.lowest_sal AND j.highest_sal;
SELECT e.last_name,e.salary,j.grade_level
from employees e,job_grades j
WHERE e.salary>= j.lowest_sal AND e.salary<=j.highest_sal;
SELECT * FROM employees;
SELECT emp.employee_id,emp.last_name,mgr.employee_id,mgr.last_name
FROM employees emp,employees mgr
WHERE emp.manager_id=mgr.employee_id;