取最大值问题。

36B 2003-04-11 02:51:49

当几个客户同时按添加时，同时处于BindingContext(ds, "tb")addnew()的状态，若按下面代码求最大值会出现重复,请问各位应如何修改？
If Me.editbh.Text = "" Then
Dim dt As DataTable = CType(ds.tb, DataTable)
Dim dr As DataRow() = dt.Select("2>1", "bh Desc")
If getpos(ds.Tables(0), dr(0).Item("bh"), "bh") = (Me.ds.Tables("tb").Rows.Count - 1) Then
Me.editbh.Text = dr(0).Item("bh") + 2
Else
Me.editbh.Text = dr(0).Item("bh") + 1
End If
end if

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saucer 2003-04-14

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you want to study on concurrency control, since it is your data, you have to decide on your own

Concurrency Control in ADO.NET
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vboridataupdatesconcurrency.asp

Tackle Data Concurrency Exceptions Using the DataSet Object
http://msdn.microsoft.com/msdnmag/issues/03/04/DataConcurrency/default.aspx

Dugu_Niu 2003-04-11