可以
外部联接分为左外部联接和右外部联接左外部联接
SELECT employee_id, manager_id
FROM employees
WHERE employees.manager_id(+) = employees.employee_id;右外部联接
SELECT employee_id, manager_id
FROM employees
WHERE employees.manager_id = employees.employee_id(+);
外部联接分为左外部联接和右外部联接左外部联接
SELECT employee_id, manager_id
FROM employees
WHERE employees.manager_id(+) = employees.employee_id;右外部联接
SELECT employee_id, manager_id
FROM employees
WHERE employees.manager_id = employees.employee_id(+);
select * from table1 a ,table2 b where a.id=b.id(+)
select * from table1 a ,table2 b where a.id(+)=b.id
可我明明在student表中是有该记录的,而在beds表中是没有学号为996211026的记录
比如。b,c对a做左连接?