title: Store Bit field Boolean Indicator in 1 or 2 columns in the database?
body: <p>I have the need for the following <code>bit</code> fields/columns in the database:</p>
  
  <p><code>IsInbound</code>
  <code>IsOutbound</code></p>
  
  <p>Now, if <code>IsInbound</code> is <code>false (0)</code>, than the inverse is exactly true which means <code>IsOutbound</code> is <code>true (1)</code>.</p>
  
  <p>I can obviously create only a single column in my table in the database with either title, and be able to extract the information required based on <code>true/false</code> conditions.</p>
  
  <p>However which is the <em>correct</em> way to design this? Do I just arbitrarily pick one of the fields and know the opposite value indicates <code>true/false</code> or should I be explicit and have <em>both</em> fields defined on the table? I've done it both ways over the years and was curious what is the correct design pattern for creating these fields?</p>