SELECT A01.ID,A02.ID,....
FROM A01 FULL JOIN A02 ON A01.ID=A02.ID
FULL JOIN A03 ON A01.ID=A03.ID AND A03.ID=A02.ID
...
FROM A01 FULL JOIN A02 ON A01.ID=A02.ID
FULL JOIN A03 ON A01.ID=A03.ID AND A03.ID=A02.ID
...
表A01(A0102, A0103):有数据
表A02(A0201,A0202):无数据
表A03(A0302,A0303):有数据
现在得到结果如下:
A0102, A0103, A0201, A0202, A0302, A0303
有内容, 有内容,空, 空, 有内容,有内容
FROM A01 FULL JOIN A02 ON A01.ID=A02.ID
FULL JOIN A03 ON A01.ID=A03.ID AND A03.ID=A02.ID
...