title: Group by month in SQLite
body: <p>I have an SQLite database which contains transactions, each of them having a <em>price</em> and a <em>transDate</em>.</p>
  
  <p>I want to retrieve the sum of the transactions grouped by month. The retrieved records should be like the following:</p>
  
  <pre><code>Price    month
  230        2
  500        3
  400        4
  </code></pre>