title: How many foreign keys is too many?
body: <p>After running across this article:
  <a href="http://diovo.com/2008/08/are-foreign-keys-really-necessary-in-a-database-design/" rel="noreferrer">http://diovo.com/2008/08/are-foreign-keys-really-necessary-in-a-database-design/</a></p>
  
  <p>It seems like a good idea to use foreign keys when designing a database. But when are you using too many?</p>
  
  <p>For example, suppose I have a main table used to store a list of machinery part information that other programs make reference to with the following columns:</p>
  
  <ol>
  <li>ID</li>
  <li>Name</li>
  <li>Colour</li>
  <li>Price</li>
  <li>Measurement Units</li>
  <li>Category</li>
  <li>etc...</li>
  </ol>
  
  <p>Should I be making tables containing a list of all possible colours, units and categories and then setting these as foreign keys to the corresponding columns in my machine part info table? At what point would the benefit of using foreign keys out weight the fact that I'm making all these extra tables and relationships?</p>