concurrency violation??

[jinte]

Hi guys,

I tried to search the forum on the topic 'concurrency violation' but I couldn't find much, so I make a new post of my problem.

The problem is the following: I try to make a database application (access 2000) which can be simultaneously used by multiple users. I added a (simplified) sample so you can test it yourself if you want.

I use a datagrid to show the contents of a datasource with only one table : tblTest. I used the dataadapter wizard to create the oledbdataadapter and I used the 'optimistic concurrency' setting in the wizard.

If two users try to adapt the same field in het datagrid and the try to update it, then a dbexception is created which warns the user. This part works fine. After this message the user has to get two choices:
1. view the changes (this is simple : refill the dataset)
2. don't view the changes and update the datasource with the values he changed.

Option 2 doesn't work : when the user selects this option I always get this message : concurrency violation , 0 rows affected.

I assume this means there aren't any changes to the dataset, but this can't be because there are changes?

PS: i simulate two simultaneous users by running two times the .exe

What Am I doing wrong??

Here is the code:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
        Me.OleDbConnection1.Open()
        Me.OleDbDataAdapter1.Fill(DStest, "tblTest")
        Me.OleDbConnection1.Close()
 
        Me.DataGrid1.DataSource = DStest
        Me.DataGrid1.DataMember = "tblTest"
 
    End Sub
 
 
    Private Sub btnUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUpdate.Click
        Dim messagestring As String
        messagestring = "Data has been changed since you opened it.  Do you want to see the changes or update the datasource with your changes.  Click 'Ja' to view the changes; click 'Nee' to pass your changes to the datasource."
 
        Try
            Me.BindingContext(DStest, "tblTest").EndCurrentEdit()
            Me.OleDbDataAdapter1.Update(DStest, "tblTest")
        Catch dbcEX As Data.DBConcurrencyException
            Dim dResult As DialogResult
            dResult = MessageBox.Show(messagestring, "There was a concurrency", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Error)
            If dResult = DialogResult.Yes Then
                Me.DStest.Clear()
                OleDbConnection1.Open()
                Me.OleDbDataAdapter1.Fill(DStest, "tblTest")
                OleDbConnection1.Close()
            ElseIf dResult = DialogResult.No Then
                'MsgBox(DAtest.UpdateCommand.ExecuteNonQuery.ToString)
                Me.OleDbDataAdapter1.Update(DStest, "tbltest")
            End If
 
        End Try
    End Sub

In attachment you can find the code and the database. If you want to try it, but the database in your C:root.

Many thanks