title: SQL Find missing date ranges
body: <p>I have a table that holds all the days/months of the year</p>
  
  <p>E.G.</p>
  
  <pre><code>Day      Month
  1         9
  2         9
  3         9
  4         9
  5         9
  6         9
  7         9
  ...       ...
  </code></pre>
  
  <p>I have a table which shows the date ranges from different datasets</p>
  
  <p>E.G.</p>
  
  <pre><code> DataSet    DateRange
  webshop 2013-09-20
  webshop 2013-09-21
  webshop 2013-09-22
  webshop 2013-09-23
  webshop 2013-09-24
  webshop 2013-09-25
  webshop 2013-09-26
  webshop 2013-09-27
  webshop 2013-09-28
  webshop 2013-09-29
  webshop 2013-09-30
  </code></pre>
  
  <p>How would I compare the two tables to show which days are missing from the DataSet for that particular month</p>
  
  <p>E.G. for my example above where the dataset is <code>webshop</code> it is missing the date range 01/09/2013 - 19/09/2013</p>
  
  <p>Thanks for any help!</p>