update row from datagridview to database

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VB

Hi all
I have a script to update the value from datagridview to database
I do use a button insert ToolStripButton
but not working
hope people to help
thank !

Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

       conn = New SqlConnection("")
       conn.Open()
       Dim query As [String] = "SELECT * FROM dtaTraLoiChoVanBan"
       da = New SqlDataAdapter(query, conn)
       Dim cb As New SqlCommandBuilder(da)
       dt = New DataTable()
       da.Fill(dt)
       C1FlexGrid1.DataSource = dt
       conn.Close()

   End Sub
 Private Sub ToolStrip1_ItemClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ToolStripItemClickedEventArgs) Handles ToolStrip1.ItemClicked
       Select Case e.ClickedItem.Name
           Case "ToolStripButton1" '---> button insert
               da.Update(dt)

       End Select
   End Sub