BOM算法问题

[wofan]

ID parentid level level bomid
----------------------------------------------------
487 0 1 + 275
488 487 2 ++ 41
489 488 3 +++ 2098
490 489 4 ++++ 824
491 490 5 +++++ 825
492 491 6 ++++++ 784
493 487 2 ++ 41
494 487 2 ++ 41
495 487 2 ++ 41
496 487 2 ++ 41
497 496 3 +++ 2099
498 497 4 ++++ 823
499 498 5 +++++ 827
500 499 6 ++++++ 785
501 0 1 + 275
502 0 1 + 275

根据level将ID填入parentid中,以上是已经填好的
我写了一个只能填一部分id 493-496无法算了

update hzkf_xx set parentid=levelno-1
declare @id nvarchar(20)
declare @parentid nvarchar(20)
declare @levelno int
declare @cid int
declare @level1 int
declare @tlevel int
declare @tparentid int

DECLARE BOM CURSOR FOR
select ID,ParentID,levelno
from hzkf_xx
open BOM
FETCH NEXT FROM BOM
into @id,@parentid,@levelno

WHILE @@FETCH_STATUS = 0
BEGIN

if (@levelno=1)
begin
set @tparentid=@parentid
set @tlevel=@id
set @cid=@id
set @level1=@levelno
--print @id
end
if (@levelno>1)
begin
if (@levelno>@level1)
begin
update hzkf_xx set parentid=@cid where id=@id
set @cid=@id
set @level1=@levelno
end

end
if (@levelno<=@level1)
begin
set @cid=@id
set @level1=@levelno
end


FETCH NEXT FROM BOM
into @id,@parentid,@levelno
END

CLOSE BOM
DEALLOCATE BOM

[csdyyr]

DECLARE @TB TABLE([ID] INT, [parentid] INT, [level] INT, [level2] VARCHAR(6), [bomid] INT)
INSERT @TB 
SELECT 487, 0, 1, '+', 275 UNION ALL 
SELECT 488, 487, 2, '++', 41 UNION ALL 
SELECT 489, 488, 3, '+++', 2098 UNION ALL 
SELECT 490, 489, 4, '++++', 824 UNION ALL 
SELECT 491, 490, 5, '+++++', 825 UNION ALL 
SELECT 492, 491, 6, '++++++', 784 UNION ALL 
SELECT 493, 487, 2, '++', 41 UNION ALL 
SELECT 494, 487, 2, '++', 41 UNION ALL 
SELECT 495, 487, 2, '++', 41 UNION ALL 
SELECT 496, 487, 2, '++', 41 UNION ALL 
SELECT 497, 496, 3, '+++', 2099 UNION ALL 
SELECT 498, 497, 4, '++++', 823 UNION ALL 
SELECT 499, 498, 5, '+++++', 827 UNION ALL 
SELECT 500, 499, 6, '++++++', 785 UNION ALL 
SELECT 501, 0, 1, '+', 275 UNION ALL 
SELECT 502, 0, 1, '+', 275


SELECT ID,
	CASE WHEN [parentid]=0 THEN 0 ELSE (SELECT TOP 1 ID FROM @TB WHERE ID<T.ID AND LEVEL=T.LEVEL-1 ORDER BY ID DESC) END AS PID,
	LEVEL,
	LEVEL2,
	BOMID
FROM @TB AS T
/*
ID          PID         LEVEL       LEVEL2 BOMID
----------- ----------- ----------- ------ -----------
487         0           1           +      275
488         487         2           ++     41
489         488         3           +++    2098
490         489         4           ++++   824
491         490         5           +++++  825
492         491         6           ++++++ 784
493         487         2           ++     41
494         487         2           ++     41
495         487         2           ++     41
496         487         2           ++     41
497         496         3           +++    2099
498         497         4           ++++   823
499         498         5           +++++  827
500         499         6           ++++++ 785
501         0           1           +      275
502         0           1           +      275

(16 行受影响)
*/

[csdyyr]

SELECT ID,
CASE WHEN LEVEL=1 THEN 0 ELSE (SELECT TOP 1 ID FROM @TB WHERE ID<T.ID AND LEVEL=T.LEVEL-1 ORDER BY ID DESC) END AS PID,
LEVEL,
LEVEL2,
BOMID
FROM @TB AS T

[guohua1205]

学习中！

[guyixin]

学习，看不懂

[htl258_Tony]

SELECT ID,
	PID=ISNULL((SELECT TOP 1 ID FROM tb WHERE ID<T.ID AND LEVEL=t.LEVEL-1 ORDER BY ID DESC),0),
	LEVEL,
	LEVEL2,
	BOMID
FROM tb t

[yhtapmys]

友情UP