对于制造多品种产品的企业，产品与零部件的关系不再是简单的一对多而是多对多关系。由于大量通用件在不同产品间的相互借用，在树状结构中表现为不同的结点可以有相同的子树；即使在同种产品内部，由于一些标准件的重用，同样使零部件关系呈现出复杂的交织。
在SQL SERVER 2000下测试通过BOM遍历算法，更深入具体的可以继续深入：
if exists (select * from dbo.sysobjects where id = object_id(N’[dbo].[Bom]’) and OBJECTPROPERTY(id, N’IsUserTable’) = 1)
drop table [dbo].[Bom]
GO
CREATE TABLE [dbo].[Bom] (
[ID] [int] IDENTITY (1, 1) NOT NULL ,
[Parentid] [varchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL ,
[Childid] [varchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL ,
[Usage] [float] NOT NULL ,
[Price] [money] NOT NULL ,
[StartDate] [smalldatetime] NOT NULL ,
[EndDate] [smalldatetime] NOT NULL
) ON [PRIMARY]
GO
CREATE PROCEDURE [dbo].[QueryBom]
(
@Itemid varchar(50),--根物料编码
@num float --物料用量
)
AS
create table [work]--创建临时表显示物料层次
(
Lvl int,--层次码
itemid varchar(50),-- 物料代码
usage float --用量
)
create table [result]--创建查询结果表
(
Seq int IDENTITY (1, 1) NOT NULL,--序号
Lvl int,--层次码
itemid varchar(50),--物料代码
usage float --用量
)
declare @lvl int, @curr varchar(50),@usage float
select top 1 @lvl=1,@curr=@Itemid ,@usage=@num from Bom --查询物料为A,需求数量为30
insert into [work](lvl,itemid,usage) values (@lvl,@curr,@usage)
while(@lvl>0)
begin
if exists (select * from [work] where lvl=@lvl)
begin
select top 1 @curr=itemid,@usage=usage from [work] where lvl=@lvl
insert [result](lvl,itemid,usage) values (@lvl,@curr,@usage)
delete [work] where lvl=@lvl and itemid=@curr
insert into [work]
select @lvl+1,Childid,usage
from Bom where Parentid=@curr and Parentid<>Childid
if(@@rowcount>0)
set @lvl=@lvl+1
end
else
set @lvl=@lvl-1
end
select * from [result]--展开Bom
select itemid,SUM(usage)*(select usage from [result] where Lvl=’1’ and Seq=’1’) from [result] where
Lvl<>’1’ group by itemid--求合计需求物料总数
drop table [work]
drop table [result]
GO
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