How to retrieve multiple rows form database to datagridview?

[acaisan]

Hye all. I need some help. Iam using vb.net 2010 and MS Acsess 2013. I have problem when retrieve multiple rows from database to datagridview. All rows have the same identification number(RFID Card No.).I want to record how many times the card had scan. Please help me here. Thanks for advance.

Public Sub updateTextBox()
        data = data + myComPort.ReadExisting()
        If Len(data) = 12 Then

            Dim i As Integer
            Dim newdata As Boolean = True
            For i = 0 To (grid.Rows.Count - 1)
                If grid.Rows.Item(i).Cells(0).Value = Microsoft.VisualBasic.Mid(data, 6, 6) Then
                    newdata = False
                    Exit For
                Else
                    newdata = True
                End If
            Next
            If newdata = True Then
                Dim gr As Integer
                gr = grid.Rows.Add()
                grid.Rows.Item(gr).Cells.Item(0).Value = Microsoft.VisualBasic.Mid(data, 6, 6)
                grid.Rows.Item(gr).Cells.Item(3).Value = DateString() + " " + TimeString()
                Notify.BalloonTipTitle = "New Tag"
                Notify.BalloonTipText = Microsoft.VisualBasic.Mid(data, 6, 6)
                Notify.ShowBalloonTip(2000)

                Try
                    cn = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Afeeq\Documents\Database2.accdb")
                    cn.Open()

                    str = "insert into table1 (Tag, L_Scan) values('" & grid.Rows.Item(grid.RowCount() - 1).Cells.Item(0).Value & " ','" & grid.Rows.Item(grid.RowCount() - 1).Cells.Item(3).Value & "')"
                    'string stores the command and CInt is used to convert number to string
                    cmd = New OleDbCommand(str, cn)
                    icount = cmd.ExecuteNonQuery
                    'MessageBox.Show(icount)
                    'displays number of records inserted
                Catch e2 As Exception
                    MessageBox.Show(e2.ToString)
                End Try
                cn.Close()

            Else
                grid.Rows.Item(i).Cells.Item(3).Value = DateString() + " " + TimeString()
                grid.Rows.Item(i).Selected = True
                Notify.BalloonTipTitle = "Tag Scanned"
                Notify.BalloonTipText = Microsoft.VisualBasic.Mid(data, 6, 6)
                Notify.ShowBalloonTip(2000)

                Try
                    cn = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Afeeq\Documents\Database2.accdb")
                    cn.Open()

                    str = "update table1 SET L_Scan = '" & grid.Rows.Item(i).Cells.Item(3).Value & "' where Tag = '" & grid.Rows.Item(i).Cells.Item(0).Value & "'"
                    'string stores the command and CInt is used to convert number to string
                    cmd = New OleDbCommand(str, cn)
                    icount = cmd.ExecuteNonQuery
                    'MessageBox.Show(icount)
                    'displays number of records inserted
                Catch e2 As Exception
                    MessageBox.Show(e2.ToString)
                End Try
                cn.Close()

            End If
            myComPort.DtrEnable = False
            RadioButton1.Enabled = False
            RadioButton2.Checked = True

            If CheckBox1.Checked = True Then
                Beep()
            End If

            Dim timeOut As DateTimeOffset = Now.AddMilliseconds(1500)
            Do
                Application.DoEvents()
            Loop Until Now > timeOut
            data = myComPort.ReadExisting()
            myComPort.DiscardInBuffer()
            data = ""
            myComPort.DtrEnable = True
            RadioButton1.Enabled = True
            RadioButton1.Checked = True

        End If
    End Sub

[Begginnerdev]

I would suspect your select/fill code to have a fixed index.

Have you checked to make sure?

Or am I misunderstanding the question?