Is postback works only in pageload?

[Bllen]

May be this question seems illogical but i want to explore it.I have if statement and i want to postback page within that statement but not in page load.my code is \[code\]if (Request.QueryString["HotelID"] != null) { //here i want to set autopostback true }\[/code\]so my page post back when it have query string.