asp.net - Error Handling in Web Form -

i'm trying cater error in data access layer, return int of value -1. see below:

protected void folderbtn_click(object sender, eventargs e) {     if (page.isvalid)     {         try         {             docsdalc dalc = new docsdalc();              // updating 2 tables here - folders , folderaccess tables              // - ado.net transaction             int folderid = dalc.createfolder(...);              if (folderid > 0)             {                 response.redirect(request.url.tostring(), false);                  // re-construct include newly-created folderid              }             else             {                 // how throw error here?             }         }         catch (exception ex)         {             handleerrors(ex);         }     } } 

if data layer returns -1, how can throw error within try block?

as following - however, since catching errors, if know it's problem, better call overload of handleerrors method pass in string defining problem, rather throw exception (which costly do).

if still want throw exception:

        if (folderid > 0)         {             response.redirect(request.url.tostring(), false);              // re-construct include newly-created folderid          }         else         {             throw new exception("database returned -1 createfolder method");         } 

a possible alternative:

        if (folderid > 0)         {             response.redirect(request.url.tostring(), false);              // re-construct include newly-created folderid          }         else         {             handleerrors("database returned -1 createfolder method");         } 

with of course overloaded handleerrors method.