WinForm+Access主从表绑定修改主表数据出错(而Sqlserver不会)

各位好，我用 C# WinForm+Access 做单据式的界面，绑定主从表时子表操作都没问题，但一修改主表，再保存就出错，提示[由于表 'BillDetail' 中了包含相关记录，不能删除或改变该记录。]。其实我并没修改主表的主键或其他有关联的数据，只是修改了一些备注的文字信息也是如此，不知何故？
我尝试换成SqlServer数据库，结构都一样，却没有此问题，不知何故？
千万别告诉我，将关系删除，我相信是有关系的问题，但不是关系的错。

图一：Access数据库结构：



图二：Sqlserver数据库结构



图三：WinForm界面与控件



以下是SqlSever的建库脚本，Access的结构也一样，WinForm中基本没什么自己写的代码，都是生成的。

if exists (select * from sysobjects where id = OBJECT_ID('[Products]') and OBJECTPROPERTY(id,

'IsUserTable') = 1)

DROP TABLE [Products]

GO

CREATE TABLE [Products] (

[Pkid] [int] IDENTITY (1, 1) NOT NULL ,

[ProductCode] [char] (8) COLLATE Chinese_PRC_CI_AS NOT NULL ,

[ProductName] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL ,

CONSTRAINT [PK_Products] PRIMARY KEY CLUSTERED

(

[Pkid]

) ON [PRIMARY]

) ON [PRIMARY]

GO

SET IDENTITY_INSERT [Products] ON

INSERT [Products] ([Pkid],[ProductCode],[ProductName]) VALUES ( 2,'F0501200','绿茶洗发水')

INSERT [Products] ([Pkid],[ProductCode],[ProductName]) VALUES ( 3,'M0602600','香草沐浴露')

INSERT [Products] ([Pkid],[ProductCode],[ProductName]) VALUES ( 4,'C0518500','芦荟洗手液')

SET IDENTITY_INSERT [Products] OFF

GO

--------------------

if exists (select * from sysobjects where id = OBJECT_ID('[Bill]') and OBJECTPROPERTY(id,

'IsUserTable') = 1)

DROP TABLE [Bill]

GO

CREATE TABLE [Bill] (

[Guid] [uniqueidentifier] NOT NULL ,

[BillDateTime] [datetime] NOT NULL ,

[Person] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL ,

CONSTRAINT [PK_Bill] PRIMARY KEY CLUSTERED

(

[Guid]

) ON [PRIMARY]

) ON [PRIMARY]

GO

INSERT [Bill] ([Guid],[BillDateTime],[Person]) VALUES ( 'b0caaa95-339c-4de7-b1ad-

1b0fadf78103','2008-12-02 23:55:00','唐古拉山')

INSERT [Bill] ([Guid],[BillDateTime],[Person]) VALUES ( '23704e6a-eca6-4622-9fe1-

caa7a3aa8eca','2007-09-24 8:23:00','李飞')

GO

--------------------

if exists (select * from sysobjects where id = OBJECT_ID('[BillDetail]') and OBJECTPROPERTY(id,

'IsUserTable') = 1)

DROP TABLE [BillDetail]

GO

CREATE TABLE [BillDetail] (

[Guid] [uniqueidentifier] NOT NULL ,

[LineNum] [int] NOT NULL ,

[ProductId] [int] NOT NULL ,

[Quantity] [decimal](18, 4) NOT NULL ,

[Price] [decimal](18, 4) NOT NULL ,

[Remark] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NULL ,

CONSTRAINT [PK_BillDetail] PRIMARY KEY CLUSTERED

(

[Guid],

[LineNum]

) ON [PRIMARY] ,

CONSTRAINT [FK_BillDetail_Bill] FOREIGN KEY

(

[Guid]

) REFERENCES [Bill] (

[Guid]

),

CONSTRAINT [FK_BillDetail_Products] FOREIGN KEY

(

[ProductId]

) REFERENCES [Products] (

[Pkid]

)

) ON [PRIMARY]

GO

INSERT [BillDetail] ([Guid],[LineNum],[ProductId],[Quantity],[Price],[Remark]) VALUES (

'b0caaa95-339c-4de7-b1ad-1b0fadf78103',1,2,23.5000,66.5800,'单独发货')

INSERT [BillDetail] ([Guid],[LineNum],[ProductId],[Quantity],[Price]) VALUES ( 'b0caaa95-339c-

4de7-b1ad-1b0fadf78103',2,3,33.5000,45.5800)

INSERT [BillDetail] ([Guid],[LineNum],[ProductId],[Quantity],[Price]) VALUES ( 'b0caaa95-339c-

4de7-b1ad-1b0fadf78103',3,4,24.0000,50.0000)

INSERT [BillDetail] ([Guid],[LineNum],[ProductId],[Quantity],[Price]) VALUES ( '23704e6a-eca6-

4622-9fe1-caa7a3aa8eca',1,4,44.0000,345.0000)

INSERT [BillDetail] ([Guid],[LineNum],[ProductId],[Quantity],[Price],[Remark]) VALUES (

'23704e6a-eca6-4622-9fe1-caa7a3aa8eca',2,3,52.0000,56.7800,'补货')

INSERT [BillDetail] ([Guid],[LineNum],[ProductId],[Quantity],[Price]) VALUES ( '23704e6a-eca6-

4622-9fe1-caa7a3aa8eca',3,2,23.5000,66.8000)

GO

呵呵，自己解决了。

观察了“TableAdapter”的“UpdateCommand”的SQL语句，哇，一大把：

UPDATE Bill

SET [Guid] = ?, BillDateTime = ?, Person = ?

WHERE ([Guid] = ?) AND (? = 1) AND (BillDateTime IS NULL) AND (? = 1) AND

(Person IS NULL) OR

([Guid] = ?) AND (BillDateTime = ?) AND (? = 1) AND (Person IS NULL) OR

([Guid] = ?) AND (? = 1) AND (BillDateTime IS NULL) AND (Person = ?) OR

([Guid] = ?) AND (BillDateTime = ?) AND (Person = ?)

去除它的“使用开放式并发”后：

UPDATE Bill

SET [Guid] = ?, BillDateTime = ?, Person = ?

WHERE ([Guid] = ?)

现在好看了……哇！为何要Update Guid字段，它是主键，不会变的！好，改掉它的！

UPDATE Bill

SET BillDateTime = ?, Person = ?

WHERE ([Guid] = ?)

现在没问题了罗。

心得：

(1)、微软的IDE是方便快捷，但在没明白它都给你干了些啥之前，最好别用它。

(2)、搞不懂MS ACCESS，Update 自己=自己这样的语句也是导致了修改事件？而SQL Server则不会。