Dim tbprev As New dbProvaDataSet.TBProvaDataTable
    ' Dim taprev As New dbProvaDataSetTableAdapters.TBProvaTableAdapter
    Dim tb As New dbProvaDataSet.TBProvaDataTable
    Dim ta As New dbProvaDataSetTableAdapters.TBProvaTableAdapter

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        tb.Rows(0)(1) = TextBox1.Text
        ta.Update(tb)

        DataGridView1.Refresh()
        DataGridView1.DataSource = tb

    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        tb = tbprev.Copy
        ta.Update(tb)

        DataGridView1.Refresh()
        DataGridView1.DataSource = tb

    End Sub


    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        tb = ta.GetData
        tbprev = ta.GetData

        DataGridView1.DataSource = tb

    End Sub