数据表中记录：
Id              Name        ParentId
1               A               0
2               a1              1
3               B               0
4               C               0
5               a2              1
6               b1              3

1：用一条SQL语句得到这个结果（大类嵌套小类）
Id              Name        ParentId
1               A               0
2               a1              1
5               a2              1
3               B               0
6               b1              3
4               C               0

2：用一条SQL语句得到这个结果（大类嵌套小类，小类汇总ParentId的值）：
Id              Name        ParentId
1               A               0
2               a1              1
5               a2              1
                小计            2
3               B               0
6               b1              3
                小计            3
4               C               0
                小计            0

--大类嵌套小类
select * from test order by Name,ParentId

------解决方案--------------------
part 1
SQL code

select id, name, pid
from (
  select id, name, pid, id as vpid
  from tb
  where parentid=0

  union

  select id, name, pid, pid as vpid
  from tb
  where parentid>0
) as a
order by vpid, pid, id

------解决方案--------------------
good

------解决方案--------------------
good

------解决方案--------------------
SQL code
if not object_id('test') is null drop table test
go
create table test(Id varchar(2),Name nvarchar(2),ParentId int)
go
insert into test
select '1','A',0 union all
select '2','a1',1 union all
select '3','B',0 union all
select '4','C',0 union all
select '5','a2',1 union all
select '6','b1',3
go

--Part 1
select * from
(
    select a.Id,a.Name,a.ParentId,sort=isnull((select b.Name from test b where a.ParentId=b.Id),a.Name) 
    from test a
) t
order by sort,ParentId
/*
Id   Name ParentId    sort
---- ---- ----------- ----
1    A    0           A
2    a1   1           A
5    a2   1           A
3    B    0           B
6    b1   3           B
4    C    0           C
*/
--Part 2
;with t as
(
    select a.Id,a.Name,a.ParentId,sort=isnull((select b.Name from test b where a.ParentId=b.Id),a.Name) from test a
)

select tt.Id,tt.Name,tt.ParentId from 
(
    select Id,Name,ParentId,sort from t
    union all
    select '',N'小计' ,count(sort)-1,sort+'1' from t
    group by sort+'1'
) tt
order by tt.sort,tt.ParentId
/*
Id   Name ParentId
---- ---- -----------
1    A    0
2    a1   1
5    a2   1
     小计   2
3    B    0
6    b1   3
     小计   1
4    C    0
     小计   0
*/