如何在查詢的時候再追加一個欄位^_^

已知:select * from Doctree輸出結果:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2_0_B.城市勘察類12  
5_2_1.工程地質12  
6_2_2.水文地質12  
7_2_3.控制測量12  
10_2_4.地形測量12  
11_10_1.文字材料12  
12_10_2.500地形圖12  
13_10_3.1000地形圖12  
14_10_4.其它比例尺12  

經過函數function f_getparent

select [key],
[parent],
[text],
[image],
[selectedimage],
case when parent='0_'
then left([text],1)
else dbo.f_getparent([parent])+'-'+left([text],1) end as str
from Doctree處理後的輸出結果:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++                                               
2_0_B.城市勘察類12   B
5_2_1.工程地質12   B-1
6_2_2.水文地質12   B-2
7_2_3.控制測量12   B-3
10_2_4.地形測量12   B-4
11_10_1.文字材料12   B-4-1
12_10_2.500地形圖12   B-4-2
13_10_3.1000地形圖12   B-4-3
14_10_4.其它比例尺12   B-4-4
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

下面是實現方法:

CREATE TABLE [dbo].[Doctree] (
[key] [nvarchar] (40) COLLATE Chinese_PRC_CI_AS NULL ,
[parent] [nvarchar] (40) COLLATE Chinese_PRC_CI_AS NULL ,
[text] [nvarchar] (200) COLLATE Chinese_PRC_CI_AS NULL ,
[image] [smallint] NULL ,
[selectedimage] [smallint] NULL
) ON [PRIMARY]
GO
insert into Doctree
select '2_','0_','B.城市勘察類',1,2
union all select '5_','2_','1.工程地質',1,2
union all select '6_','2_','2.水文地質',1,2
union all select '7_','2_','3.控制測量',1,2
union all select '10_','2_','4.地形測量',1,2
union all select '11_','10_','1.文字材料',1,2
union all select '12_','10_','2.500地形圖',1,2
union all select '13_','10_','3.1000地形圖',1,2  
union all select '14_','10_','4.其它比例尺',1,2 
go
create function f_getparent(@parent nvarchar(40))
returns varchar(1000)
as
begin
declare @key nvarchar(40)
declare @str varchar(1000)
select @str=left([text],1)+'-',@key=[parent] from doctree where [key]=@parent
while isnull(@key,'')<>'0_'
begin
select @str=@str+left([text],1)+'-',@key=[parent] from doctree where [key]=@key
end
return reverse(left(@str,len(@str)-1))
end