Dataset Question

Hello,

I am updating an access database using a dataset. My question is... how come I can add a record to a table that doesn't have a primary key defined, but I cannot update a specified record? Here is the code that I am using...

Code:

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            Dim cn As New OleDbConnection(AppSettings("cnString"))
            Dim da As New OleDbDataAdapter("SELECT * FROM tblEmailAddresses", cn)
            Dim ds As New DataSet()
            Dim dv As DataView
            Dim dr As DataRow

            da.Fill(ds, "tblEmail")
            'check if the customer's email has already been added
            dv = ds.Tables("tblEmail").DefaultView
            dv.RowFilter = "Email=" & "'" & strEmail & "'"
            If dv.Count > 0 Then
                'this email was already added
                dv(0).Item("Promotions") = blnAgree
                dv(0).Item("Name") = strName
            Else
                dr = ds.Tables("tblEmail").NewRow()
                dr("Name") = strName
                dr("Email") = strEmail
                ds.Tables("tblEmail").Rows.Add(dr)
            End If

            'update the Email Address table in the database
            cn.Open()
            da.MissingSchemaAction = MissingSchemaAction.AddWithKey
            Dim cmd As New OleDbCommandBuilder(da)
            da.Update(ds, "tblEmail")

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The above code works perfectly if a primary key is defined in the access table. I also tried substituting MissingSchemaAction.AddWithKey with MissingSchemaAction.Add and this didn't work either.

The DataAdapter uses a primary key to make updates. If you dont have a primary key, you can supply your own updating logic in a commandBuilder and pass it to the DataAdapter.