รบกวนพี่ ๆช่วยอธิบาย Code ให้ส่วนนี้ไห้ผมหน่อยครับ ผมงงจริง ๆเลย

  '/////sql insert
            Dim strselectinsert As String = "insert into staff (StaffID,Name,Lname,Address,Username,Password,Tel,Email) values ('" + StaffIDTextBox.Text + "','" + NameTextBox.Text + "','" _
                                    + LnameTextBox.Text + "','" + AddressTextBox.Text + "','" + UsernameTextBox.Text + "','" + PasswordTextBox.Text + "','" + TelTextBox.Text + "','" + EmailTextBox.Text + "')"
            '/////sql update
            Dim strselectupdate As String = "update Staff set StaffID = '" + StaffIDTextBox.Text + _
                   "',Name='" + NameTextBox.Text + "',Lname='" + LnameTextBox.Text + "',Address='" + AddressTextBox.Text _
                   + "',Username='" + UsernameTextBox.Text + "',Password='" + PasswordTextBox.Text + "',Tel='" + TelTextBox.Text _
                   + "',Email='" + EmailTextBox.Text + "' where StaffID='" + StaffIDTextBox.Text + "'"
            Dim com As New SqlCommand
            com.CommandType = CommandType.Text
            Dim cf As Integer
            Dim i As Integer
            While i < StaffDataGridView.Rows.Count
                If StaffIDTextBox.Text = StaffDataGridView.Rows(i).Cells(0).Value Then
                    cf = 1
                    Exit While
                End If
                i += 1
            End While
            If cf Then
                com.CommandText = strselectupdate
            Else
                com.CommandText = strselectinsert  
            End If
            i = 0
          
            com.Connection = con        
            com.ExecuteNonQuery()      
            Me.StaffTableAdapter.Fill(Me.CarDataSet.Staff) '//รีเฟช datagridview database
            MsgBox("ทำการเปลียนแปลงข้อมูลเรียบร้อยแล้ว", MsgBoxStyle.Information, "สำเร็จ")