title: Count combinations of packages (row values) per user (unique value)
body: <p>Consider the following:</p>
  
  <pre><code>customer, package
  a, pack1
  a, pack2
  b, pack1
  c, pack1
  c, pack2
  d, pack3
  d, pack2
  d, pack1
  e, pack1
  e, pack3
  f, pack1
  f, pack2
  f, pack3
  </code></pre>
  
  <p>The output I need is, how MANY unique customers have a SPECIFIC combination of package(s):</p>
  
  <pre><code> pack1, 1 
  (pack1, pack2), 2
  (pack1, pack2, pack3), 2
  (pack1, pack3), 1 
  </code></pre>
  
  <p>When I export the table to a spreadsheet (or use GNU datamash) and make a pivot table and work a little bit on that, I can sort of get what I need, but I need to count things by hand. So I keep thinking this should be simpler (without exporting the data to a pivot table).</p>
  
  <p>Any pointers are appreciated (it's late).</p>
  
  <p>There is an SQLFiddle: <a href="http://sqlfiddle.com/#!9/7bb98/1" rel="nofollow noreferrer">http://sqlfiddle.com/#!9/7bb98/1</a></p>