How to test if add or update

Hi all,

In a datagrid, how do you test if the record is being added or updated.

What I have now is :

VB Code:

Private Sub Save_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Save.Click
        Dim rowindex As Integer = DataGrid2.CurrentRowIndex
        Dim struserid As String = DataGrid2.Item(rowindex, 0)
        Dim struserpass As String = DataGrid2.Item(rowindex, 1)
        Dim sqlcmd As String
        Dim ifexistcmd As String
        ifexistcmd = "select count(*) from usermaster" & _
                    " where userid = " & obj.PrepareStr(struserid)
        If obj.recordexist(ifexistcmd) Then
            If MessageBox.Show(Me, "Confirm Update of User " & struserid, "Update Confirmation", MessageBoxButtons.OKCancel, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2, MessageBoxOptions.RightAlign) = DialogResult.OK Then
                Try
                    sqlcmd = "update usermaster set userpass=" & _
                            obj.PrepareStr(struserpass) & " where userid = " & _
                            obj.PrepareStr(struserid)
 
                    obj.UpdateRecord(sqlcmd)
 
                Catch Exp As Exception
                    MsgBox(Exp.Message, MsgBoxStyle.Critical, "General Error")
                End Try
            End If
        Else 'add 
            If MessageBox.Show(Me, "Confirm Addition of User " & struserid, "Add Confirmation", MessageBoxButtons.OKCancel, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2, MessageBoxOptions.RightAlign) = DialogResult.OK Then
                Try
                    sqlcmd = "insert into usermaster (userid, userpass, usertype) values (" & obj.PrepareStr(struserid) & "," & obj.PrepareStr(struserpass) & "," & "'" & "M" & "'" & ")"
                    obj.AddRecord(sqlcmd)
 
                Catch Exp As Exception
                    MsgBox(Exp.Message, MsgBoxStyle.Critical, "General Error")
                End Try
            End If
        End If
    End Sub

The problem here is whenever I scroll down to the last row and enter a userid that is already existing, it runs the update block since the userid is already existing, leaving me in the grid with 2 entry of the same userid. And upon refreshing the grid, will display the updated userid.

How do I accomplish the same task that if the user inputs a duplicate userid, it will display an error "Duplicate userid" without running the update block.

Any ideas???

Thanks in advance,
Marivic