title: Which approach to store static data is better?
body: <p>I am developing a web application about books. We all knows that books have different category. So, this category is basic on a sequence of number, for example, 200 = computer related, 800 = history. Each book is beyond to one category only. </p>
  
  <p>Here is the question. I have a category list, it may expand in the future. For example, new technology is appear, and new category will be created. So, what should I store this category? In a database? or a simple XML file? Because it is not alter all the time, so, I am think will it become a waste to store in database? thz u.</p>