计算bom的准确用量

DECLARE @yl decimal(18,6),@path nvarchar(800),@cd int,@cec int
　　
　　DECLARE boms CURSOR
　　FOR SELECT sl, path ,len(path),ceci FROM bomt where scbs='P' and ceci>0 -----获取是生产件的数据，根据层数逐阶展开
　　
　　--DECLARE @count smallint
　　--SELECT @count = 1
　　
　　OPEN boms
　　FETCH NEXT FROM boms INTO @yl,@path,@cd,@cec
　　WHILE (@@fetch_status <> -1)
　　BEGIN
　　-------------更新用量
　　UPDATE bomt
　　SET sl=@yl*sl
　　WHERE ceci=@cec+1 ------制定下一层，即限制它的第一阶子件，而不往下阶延伸
　　 and left(path,@cd)=@path
　　
　　 FETCH NEXT FROM boms INTO @yl,@path,@cd,@cec
　　
　　END
　　CLOSE boms
　　DEALLOCATE boms
　　
　　--------显示
　　select ceci as 层次,parent_item as 物料, itemname as 物料名称, @bz*sl as 标准设计数量, dw as 单位, ck as 仓库, fhf as 发货方法,scbs as BOM类型 from bomt order by path
　　end
　　GO