我看到了个例子发现的SELECT e.last_name, e.department_id, d.department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id); 等价于 SELECT e.last_name, e.department_id, d.department_name FROM employees e, departments d WHERE e.department_id=d.department_id(+)
只是两种连接的写法 这个是固定格式!记住就是 如果用上 left outer join 就ON 如果没有就用where 就是了!
FROM employees e
LEFT OUTER JOIN departments d
ON (e.department_id = d.department_id); 等价于
SELECT e.last_name, e.department_id, d.department_name
FROM employees e, departments d
WHERE e.department_id=d.department_id(+)
这个是固定格式!记住就是
如果用上 left outer join 就ON
如果没有就用where 就是了!