replace values in the QueryString key/value pairs

The URL with a  QueryString is something like “apage.aspx?month=10&year=2006&…”, anything in Request.QueryString cannot be changed because it is readonly, but the values of “month” and “year” can be changed as followed:

NameValueCollection nvc = HttpUtility.ParseQueryString(Request.QueryString.ToString());

nvc.Set(“month”, “12″);

nvc.Set(“year”, “2009″);

string newUrl = this.Request.ServerVariables["URL"].ToString() + “?” + nvc.ToString() ;