There are two ways to narrow a search. To do a true "search within results" you need to return a result set with the first search, then only search that result set for matches with the second parameters.
If you don't really require such a function, then you can simply add on additional requirements (WHERE statement) to your SQL, and run the query once.
The latter is more efficient, but you have more control over the results with the first way. You could sort the first list by price, and the second iteration could be sorted a different way.
My suggesion: try both, and see which gives you the most flexibility and ease of use for what you trying to do.
