根據select語句在數據庫中獲取值

Question

對不起我的問題標題，我找不到更好的名稱。

這是我的表：

Project_ID ParentProject Projecttype 
---------------------------------------- 
20.003  20.001   P 
20.001  20    P 
20   NULL   V 
21.001  21    P 
21   NULL   V 

我要做出選擇我所有的項目與它的「upperparentproject」。我想用Projecttype = 'P' a ParentProject與Projecttype = 'V'搜索所有項目。所以這是我的結果：

Project_ID ParentProject 
-------------------------- 
20.003  20   
20.001  20     
21.001  21   

這是可能的SELECT陳述或有執行這個法子？

Answer 1

試試這個：

select *,row_number() over (order by (select 0)) as rn  into tbl1 from table1 

Declare @mn int,@mx int 
Declare @mn1 int,@mx1 int 
Declare @prjid float,@prntid varchar(10) 
DECLARE @result TABLE(prjID float,prentID varchar(10)) 

select @mn=MIN(rn),@mx=MAX(rn) from tbl1 

WHILE(@mn<=@mx) 
BEGIN 
select @prjid=Project_id,@prntid=ParentProject from tbl1 where rn=@mn and ProjectType='P' 
select @mn1=MIN(rn),@mx1=MAX(rn) from tbl1 

WHILE(@mn1<=@mx1) 
BEGIN 
select @prntid=CASE WHEN ParentProject IS NOT NULL then ParentProject else @prntid end from tbl1 where Project_id=@prntid and rn = @mn1 
SET @mn1=@mn1+1 
END 

INSERT INTO @result 
values(@prjid,@prntid) 

SET @mn=@mn+1 
END 
select distinct * from @result