[打卡]陈天宇 多表查询2

SELECT employee_id,department_name
FROM employees e LEFT JOIN departments d
ON e.department_id = d.department_id;

SELECT employee_id,department_name
FROM employees e RIGHT JOIN departments d
ON e.department_id = d.department_id;

SELECT employee_id,department_name FROM employees e FULL OUTER JOIN departments d
ON e.department_id = d.department_id;

SELECT employee_id,department_name
FROM employees e JOIN departments d
ON e.department_id = d.department_id;

SELECT employee_id,department_name
FROM employees e,departments d
WHERE e.department_id = d.department_id;

SELECT employee_id,department_name
FROM employees e LEFT JOIN departments d
ON e.department_id = d.department_id
WHERE d.department_id is null;

SELECT employee_id,department_name
FROM employees e RIGHT JOIN departments d
ON e.department_id = d.department_id
WHERE e.department_id IS NULL;

SELECT employee_id,department_name
FROM employees e LEFT JOIN departments d
ON e.department_id = d.department_id
UNION ALL
SELECT employee_id,department_name
FROM employees e RIGHT JOIN departments d
ON e.department_id = d.department_id
WHERE e.department_id IS NULL;

SELECT employee_id,department_name
FROM employees e RIGHT JOIN departments d
ON e.department_id = d.department_id
UNION ALL
SELECT employee_id,department_name
FROM employees e LEFT JOIN departments d
ON e.department_id = d.department_id
WHERE d.department_id IS NULL;

SELECT employee_id,department_name
FROM employees e LEFT JOIN departments d
ON e.department_id = d.department_id
WHERE d.department_id IS NULL
UNION ALL
SELECT employee_id,department_name
FROM employees e LEFT JOIN departments d
ON e.department_id = d.department_id
WHERE e.department_id IS NULL;