title: Detect overlapping date ranges from the same table
body: <p>I have a table with the following data</p>
  
  <pre><code>PKey  Start       End         Type
  ====  =====       ===         ====
  01    01/01/2010  14/01/2010  S
  02    15/01/2010  31/01/2010  S
  03    05/01/2010  06/01/2010  A
  </code></pre>
  
  <p>And want to get the following results</p>
  
  <pre><code>PKey  Start       End         Type
  ====  =====       ===         ====
  01    01/01/2010  14/01/2010  S
  03    05/01/2010  06/01/2010  A
  </code></pre>
  
  <p>Any ideas on where to start? A lot of the reading I've done suggests I need to create entries and for each day and join on matching days, is this the only way?</p>