Need a functional equivilant to the ASP QueryString collection

I'm writting a web application that is building a web form dynamically, and upon submission by the user, it needs to save all of the user inputs to a database. The problem is, I don't know what the names of the input elements will be. In ASP, I would iterate through the QueryString collection (e.g. For Each item In Request.QueryString), but unless I am missing it in the documentation, I don't see an equivalent in PHP. I have considered using a javascript function to iterate through the form collection on the client side, and store an array of all the form items in a hidden input, but this seems like too much of a hack. Does anyone have any better ideas?