[打卡]下课

SELECT employee_id,last_name,department_name,city
FROM employees,departments,locations
WHERE employees.department_id = departments.department_id
AND departments.location_id = locations.location_id;

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;

# 角度2：自连接（自我引用） VS 非自链接

SELECT * FROM employees;

# 查询员工ID，员工的姓名及其管理者的ID和姓名

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;

SELECT * FROM employees;