how to test if a Querystring item exists?

[Marcio Watanabe]

If I use Request.QueryString["page"] for the URL below, an empty
string is returned:
http://listorders.aspx?page=

What is returned if I use Request.QueryString["page"] for:
http://listorders.aspx

I can test the former case easily:
if (Request.QueryString["page"] == string.Empty) {

I thought that would work for the latter case too, but it doesn't.
Is there an easy way to test for the latter case?

 

[Malek]

Sorry if you didn't understand my earlier response : test for null :

if (Request.QueryString["page"] == null) {
.....