รบกวนพี่ดูโค้ดให้บ้างค่ะ ตัดสต๊อกไม่ได้อ่ะค่ะ ไมยอมลบข้อมูลให้ค่ะ

Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        updateproduct()
    End Sub
    Sub updateproduct()
        If con.State = ConnectionState.Closed Then
            con.Open()
        End If
        Dim am As String = "select * from at_product where pd_id = '" & TextBox6.Text & "'"
        Dim com As New SqlCommand(am, con)
        Dim dr As SqlDataReader = com.ExecuteReader
        Dim amount As Integer = 0
        If dr.HasRows = True Then
            dr.Read()
            amount = CInt(dr.Item(4))
            dr.Close()
            MsgBox("ข้อมูลตรงกัน")
            Dim update As String = "update at_product set pd_amount ='" & CInt(TextBox8.Text) - amount & "'"
            Dim com1 As New SqlCommand
            With com1
                .CommandType = CommandType.Text
                .CommandText = update
                .Connection = con
                .ExecuteNonQuery()
                MessageBox.Show("ทำการขายเรียบร้อย", "ผลการตรวจสอบ", MessageBoxButtons.OK, MessageBoxIcon.Information)
            End With
        Else
            dr.Close()
            MsgBox("ไม่ตรง")

        End If
        con.Close()
    End Sub