求高手帮我计算一个物资期初+收入-发出等于库存的SQL算法，谢谢！！！
期初库存：月度结转='201208'期未库存：月度结转='201209'物资入库 物资出库要求计算： 期初库存+物资入库-物资出库=期未库存(或者实时库存表) 物资编码 期初库存 物资入库 物资出库 期未库存 001 ? ? ? ? 002 ? ? ? ? 003 ? ? ? ?if exists (select * from sysobjects where id = OBJECT_ID('[实时库存表]') and OBJECTPROPERTY(id, 'IsUserTable') = 1) DROP TABLE [实时库存表]CREATE TABLE [实时库存表] ([物资编码] [varchar] (50) NULL,[数量] [decimal] (18,3) NULL,[单价] [decimal] (18,2) NULL,[金额] [decimal] (18,2) NULL)INSERT [实时库存表] ([物资编码],[数量],[单价],[金额]) VALUES ( N'001',99.000,5.00,495.00)INSERT [实时库存表] ([物资编码],[数量],[单价],[金额]) VALUES ( N'002',26.000,2.00,52.00)INSERT [实时库存表] ([物资编码],[数量],[单价],[金额]) VALUES ( N'003',60.000,3.00,190.00)if exists (select * from sysobjects where id = OBJECT_ID('[物资出库]') and OBJECTPROPERTY(id, 'IsUserTable') = 1) DROP TABLE [物资出库]CREATE TABLE [物资出库] ([物资编码] [varchar] (50) NULL,[出库数量] [decimal] (18,3) NULL,[出库单价] [decimal] (18,2) NULL,[出库金额] [decimal] (18,2) NULL,[结转日期] [varchar] (50) NULL)INSERT [物资出库] ([物资编码],[出库数量],[出库单价],[出库金额],[结转日期]) VALUES ( N'001',12.000,5.00,60.00,N'201209')INSERT [物资出库] ([物资编码],[出库数量],[出库单价],[出库金额],[结转日期]) VALUES ( N'002',6.000,2.00,12.00,N'201209')INSERT [物资出库] ([物资编码],[出库数量],[出库单价],[出库金额],[结转日期]) VALUES ( N'003',5.000,3.00,15.00,N'201209')INSERT [物资出库] ([物资编码],[出库数量],[出库单价],[出库金额],[结转日期]) VALUES ( N'001',12.000,5.00,60.00,N'201209')INSERT [物资出库] ([物资编码],[出库数量],[出库单价],[出库金额],[结转日期]) VALUES ( N'002',80.000,2.00,160.00,N'201209')INSERT [物资出库] ([物资编码],[出库数量],[出库单价],[出库金额],[结转日期]) VALUES ( N'003',90.000,3.00,370.00,N'201209')if exists (select * from sysobjects where id = OBJECT_ID('[物资入库]') and OBJECTPROPERTY(id, 'IsUserTable') = 1) DROP TABLE [物资入库]CREATE TABLE [物资入库] ([物资编码] [varchar] (50) NULL,[入库数量] [decimal] (18,3) NULL,[入库单价] [decimal] (18,2) NULL,[入库金额] [decimal] (18,2) NULL,[结转日期] [varchar] (50) NULL)INSERT [物资入库] ([物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( N'001',100.000,5.00,500.00,N'201209')INSERT [物资入库] ([物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( N'003',35.000,3.00,105.00,N'201209')INSERT [物资入库] ([物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( N'002',27.000,2.00,54.00,N'201209')INSERT [物资入库] ([物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( N'001',13.000,5.00,65.00,N'201209')INSERT [物资入库] ([物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( N'002',80.000,2.00,160.00,N'201209')INSERT [物资入库] ([物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( N'003',100.000,3.00,300.00,N'201209')if exists (select * from sysobjects where id = OBJECT_ID('[月度结转]') and OBJECTPROPERTY(id, 'IsUserTable') = 1) DROP TABLE [月度结转]CREATE TABLE [月度结转] ([序列号] [bigint] IDENTITY (1, 1) NOT NULL,[物资编码] [varchar] (50) NULL,[入库数量] [decimal] (18,3) NULL,[入库单价] [decimal] (18,2) NULL,[入库金额] [decimal] (18,2) NULL,[结转日期] [varchar] (50) NULL)ALTER TABLE [月度结转] WITH NOCHECK ADD CONSTRAINT [PK_月度结转] PRIMARY KEY NONCLUSTERED ( [序列号] )SET IDENTITY_INSERT [月度结转] ONINSERT [月度结转] ([序列号],[物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( 1,N'001',10.000,5.00,50.00,N'201208')INSERT [月度结转] ([序列号],[物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( 2,N'002',5.000,2.00,10.00,N'201208')INSERT [月度结转] ([序列号],[物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( 3,N'003',20.000,3.00,60.00,N'201208')INSERT [月度结转] ([序列号],[物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( 4,N'001',99.000,5.00,495.00,N'201209')INSERT [月度结转] ([序列号],[物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( 5,N'002',26.000,2.00,52.00,N'201209')INSERT [月度结转] ([序列号],[物资编码],[入库数量],[入库单价],[入库金额],[结转日期]) VALUES ( 6,N'003',60.000,3.00,190.00,N'201209')SET IDENTITY_INSERT [月度结转] OFF