Protected Sub btnCerca_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCerca.Click
        Dim nome As String = txtCerca.Text
        Dim sql As String = "SELECT * FROM [elenco_utenti] WHERE cognome LIKE '" & nome & "%'"

        SqlDataSource1.SelectCommand = sql

        SqlDataSource1.Select(DataSourceSelectArguments.Empty)

        GridView1.DataBind()
End Sub