自然連接
SELECT employee_id, department_name
FROM employee e JOIN department d
ON e.department_id = d.department_id
AND e.manager_id = d.manager_id;
等同于
SELECT employee_id, department_name
FROM employee e NATURAL JOIN department d;
自動查詢兩張表中所有相同的字段,然后進行等值連接
USING
SELECT employee_id, department_name
FROM employee e JOIN department d
ON e.department_id = d.department_id;
等同于
SELECT employee_id, department_name
FROM employee e JOIN department d
USING (department_id);
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