title: Locate sequential id blocks in SQLite database
body: <p>I have a SQLite table that contains a list of numbers. Looks like the following:</p>
  
  <pre><code>1
  2
  3
  8
  9
  11
  12
  13
  14
  15
  18
  19
  </code></pre>
  
  <p>I need to turn these into blocks that have sequential ids. For example, </p>
  
  <pre><code>1-3 
  8-9 
  11-15 
  18-19
  </code></pre>
  
  <p>Is this possible using just SQL, or do I need to loop through and compare previous with current...</p>