What I need to implement is that if either of the databases (oracle) are not available, server down etc, then redirect the user to another error page.

Once you create a WebPage you automatically derive from System.Web.UI.Page. The Page object helps you trap page-level errors. In order to perform this you need to override it's OnError method.

protected override void OnError(EventArgs e)
{
  
  HttpContext ctx = HttpContext.Current;
  Exception exception = ctx.Server.GetLastError (); /*here you can even analyze what kind of error occurred*/
  string errorInfo =
     "<br>Offending URL: " + ctx.Request.Url.ToString () +
     "<br>Source: " + exception.Source +
     "<br>Message: " + exception.Message +
     "<br>Stack trace: " + exception.StackTrace;
  /*If you want to redirect use Response.Redirect*/
  ctx.Response.Write (errorInfo);
  ctx.Server.ClearError ();
  base.OnError (e);
}

Regards