Dim conn As New SqlConnection("Data Source=dell-07\SQLEXPRESS; Initial Catalog=CASSAWEB;Integrated Security=SSPI")
Dim command As New SqlCommand("select * from WEB_PUBB where data_pratica between @dal and @al", conn)

command.Parameters.Add ("@dal",SqlDbType.NVarchar)
command.Parameters.Add ("@al",SqlDbType.NVarchar)

command.Parameters("@dal").Value = (Convert.toDateTime(dataProva.Text)).toString("yyyyMMdd",System.Globalization.CultureInfo.CreateSpecificCulture("it-IT"))

command.Parameters("@al").Value = (Convert.toDateTime(dataProva2.Text)).toString("yyyyMMdd",System.Globalization.CultureInfo.CreateSpecificCulture("it-IT"))

conn.Open()
Dim dr As SqlDataReader = command.ExecuteReader()