sql取合集，如何一句sql解决

sql取合集，怎么一句sql解决啊
表A
ID A1
1 a1
2 a2
3 a3

表B
ID B1
3 b3
4 b4
5 b5


想要结果
ID A1 B1
1 a1 NULL
2 a2 NULL
3 a3 b3
4 NULL b4
5 NULL b5
如何查询啊？

[解决办法]

SQL code

declare @表A table (ID int,A1 varchar(2))insert into @表Aselect 1,'a1' union allselect 2,'a2' union allselect 3,'a3'declare @表B table (ID int,B1 varchar(2))insert into @表Bselect 3,'b3' union allselect 4,'b4' union allselect 5,'b5'select isnull(a.ID,b.ID) as ID,a.A1,b.B1 from @表A a full join @表B b on a.ID=b.ID/*ID          A1   B1----------- ---- ----1           a1   NULL2           a2   NULL3           a3   b34           NULL b45           NULL b5*/