数据库中也只有一个表book，这个问题困扰我几天了，哪位大虾帮我解决一下


总是显示:未处理的“System.Data.DBConcurrencyException”类型的异常出现在 system.data.dll 中。其他信息: 并发冲突: UpdateCommand 影响 0 个记录

Dim cnn As OleDbConnection
Dim dp As OleDbDataAdapter
Dim ds As DataSet
Dim cnnStr As String
Dim sql, updatesql As String
Dim dr As DataRow

cnnStr = "provider=microsoft.jet.oledb.4.0;data source=book.mdb"

cnn = New OleDbConnection(cnnStr)

cnn.Open()
MsgBox("连接成功")

dp = New OleDbDataAdapter

sql = "select * from book"
dp.SelectCommand = New OleDbCommand(sql, cnn)

updatesql = "update book set writer=@writer,name=@name,press=@press where ID=@ID"
dp.UpdateCommand = New OleDbCommand(updatesql, cnn)

Dim paramID = New OleDbParameter("@ID", OleDbType.VarChar, 50, "ID")
Dim paramName = New OleDbParameter("@name", OleDbType.VarChar, 50, "name")
Dim paramWriter = New OleDbParameter("@writer", OleDbType.VarChar, 50, "writer")
Dim paramPress = New OleDbParameter("@press", OleDbType.VarChar, 50, "press")

dp.UpdateCommand.Parameters.Add(paramID)
dp.UpdateCommand.Parameters.Add(paramName)
dp.UpdateCommand.Parameters.Add(paramWriter)
dp.UpdateCommand.Parameters.Add(paramPress)

paramID.Sourceversion = DataRowVersion.Original

ds = New DataSet

dp.Fill(ds, "book")

dg.DataSource = ds.Tables("book")

dr = ds.Tables("book").Rows(2)
If Not (dr Is Nothing) Then
dr("writer") = txt_writer.Text
Else
MsgBox("无此记录")
End If

dp.Update(ds, "book")
cnn.Close()

MsgBox("成功")

贴出来几天了，为什么就没有人指导一下啊，难道大家都和我一样菜
帮帮忙啦！～！～！～！

谢谢指导
我改了一下，用insertcommand就可以用，但是用updatecommand就不可以了，你再帮我看了一下

可以正常运行的程序：
Dim cnn As OleDbConnection
Dim dp As OleDbDataAdapter
Dim ds As DataSet
Dim cnnStr As String
Dim sql, insertsql As String
Dim dr As DataRow

cnnStr = "provider=microsoft.jet.oledb.4.0;data source=book.mdb"

cnn = New OleDbConnection(cnnStr)

cnn.Open()
MsgBox("连接成功")

dp = New OleDbDataAdapter

sql = "select * from book"
dp.SelectCommand = New OleDbCommand(sql, cnn)

insertsql = "insert into book (writer,name,press,ID) values (?,?,?,?)"
dp.InsertCommand = New OleDbCommand(insertsql, cnn)

Dim paramID = New OleDbParameter("ID", OleDbType.VarChar, 50, "ID")
Dim paramName = New OleDbParameter("name", OleDbType.VarChar, 50, "name")
Dim paramWriter = New OleDbParameter("writer", OleDbType.VarChar, 50, "writer")
Dim paramPress = New OleDbParameter("press", OleDbType.VarChar, 50, "press")

dp.InsertCommand.Parameters.Add(paramID)
dp.InsertCommand.Parameters.Add(paramName)
dp.InsertCommand.Parameters.Add(paramWriter)
dp.InsertCommand.Parameters.Add(paramPress)

paramID.Sourceversion = DataRowVersion.Original

ds = New DataSet

dp.Fill(ds, "book")

dg.DataSource = ds.Tables("book")

dr = ds.Tables("book").NewRow

dr("writer") = txt_writer.Text
dr("ID") = txt_id.Text
dr("press") = txt_press.Text
dr("name") = txt_name.Text
ds.Tables("book").Rows.Add(dr)

　dp.Update(ds, "book")
cnn.Close()

MsgBox("成功")

不能运行的，还是出现以前的并发冲突，说是返回０行记录:
Dim cnn As OleDbConnection
Dim dp As OleDbDataAdapter
Dim ds As DataSet
Dim cnnStr As String
Dim sql, updatesql As String
Dim dr As DataRow

cnnStr = "provider=microsoft.jet.oledb.4.0;data source=book.mdb"

cnn = New OleDbConnection(cnnStr)

cnn.Open()
MsgBox("连接成功")

dp = New OleDbDataAdapter

sql = "select * from book"
dp.SelectCommand = New OleDbCommand(sql, cnn)

updatesql = "update book set writer=?,name=?,press=? where ID=?"
dp.UpdateCommand = New OleDbCommand(updatesql, cnn)

Dim paramID = New OleDbParameter("ID", OleDbType.VarChar, 50, "ID")
Dim paramName = New OleDbParameter("name", OleDbType.VarChar, 50, "name")
Dim paramWriter = New OleDbParameter("writer", OleDbType.VarChar, 50, "writer")
Dim paramPress = New OleDbParameter("press", OleDbType.VarChar, 50, "press")

dp.UpdateCommand.Parameters.Add(paramID)
dp.UpdateCommand.Parameters.Add(paramName)
dp.UpdateCommand.Parameters.Add(paramWriter)
dp.UpdateCommand.Parameters.Add(paramPress)

paramID.Sourceversion = DataRowVersion.Original

ds = New DataSet

dp.Fill(ds, "book")

dg.DataSource = ds.Tables("book")

dr = ds.Tables("book").Rows(0)

dr("writer") = txt_writer.Text
dr("ID") = txt_id.Text
dr("press") = txt_press.Text
dr("name") = txt_name.Text

dp.Update(ds, "book")
cnn.Close()

别沉啊，问题还没有解决呢，

谢谢你，其实这个例子的其它实现方式我都做过，也能够通过，我现在想用最终用oledbdataadapter.update 的方法重新实现一下，而且不用commandbuilder,以适应复杂数据库编程的需要,我是初学者，想多了解一些ＡＤＯ．ＮＥＴ的机制,不过还是要谢谢楼上的大哥．还是要慨叹一句，这个论坛上的热心人不多啊