title: Difference between clustered and nonclustered index
body: <p>I need to add proper <code>index</code> to my tables and need some help.</p>
  
  <p>I'm confused and need to clarify a few points:</p>
  
  <ul>
  <li><p>Should I use index for <code>non-int</code> columns? Why/why not</p></li>
  <li><p>I've read a lot about <code>clustered</code> and <code>non-clustered</code> index yet I still can't decide when to use one over the other. A good example would help me and a lot of other developers. </p></li>
  </ul>
  
  <p>I know that I shouldn't use indexes for columns or tables that are often updated. What else should I be careful about and how can I know that it is all good before going to test phase?</p>