ASP.NET でデータベース接続

接続には、Microsoft SQL Server のサンプルDB を使います。
コードの本体は SqlConnection クラスです。

<%@ PAGE LANGUAGE="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<html>
<head>
<title>connect db</title>
<script runat="server">
String ok_str = "Data Source=.\\SQLExpress;Integrated Security=sspi;";
String ng_str = "Data Source=.\\SQLExpres;Integrated Security=sspi;Connection Timeout=1;";
void connect_test(Object sender, CommandEventArgs e)
{
  String connection_string = "";
  switch(e.CommandName)
  {
    case "ok_test":
      connection_string = ok_str;
      break;
    default:
      connection_string = ng_str;
      break;
  }
  using (SqlConnection con = new SqlConnection(connection_string))
  {
    try
    {
      con.Open();
      con.Close();
      lbl_result.Text = "connect success";
    }
    catch(SqlException sqle)
    {
      lbl_result.Text = sqle.Message;
    }
  }
}
</script>
</head>
<body>
  <form runat="server">
  <asp:Button id="btn_connectdb1"
       Text="Connect DB"
       CommandName="ok_test"
       OnCommand="connect_test"
       runat="server" />
  <asp:Button id="btn_connectdb2"
       Text="Fail DB"
       CommandName="ng_test"
       OnCommand="connect_test"
       runat="server" /><br>
  <asp:Label id="lbl_result" Text="" runat="server" />
  </form>
</body>
</html>