请问如下3条语句结果是否相同？

1、标准外关联：
SELECT A.C1, A.C2, B, C1, B.C2 FROM A LEFT OUTER JOIN B ON (A.C1 = B.C1 AND A.C2 = B.C2);

2、ORACLE写法1：

SELECT A.C1, A.C2, B, C1, B.C2
FROM A, B
WHERE A.C1 = B.C1(+)
AND A.C2 = B.C2(+);

3、ORACLE写法2：
此种写法是否可以？

SELECT A.C1, A.C2, B, C1, B.C2
FROM A, (SELECT C1, C2, C1 || C2 C12 FROM B) B
WHERE A.C1 || A.C2 = B.C12(+)