title: GROUP BY expression (part of column) instead of whole column
body: <p>I'm creating a query:
  I need to get the quantity of returns made for each year.</p>
  
  <p><code>ReturnDate</code> is the specific date each member has, when the return was made.
  To get the year I'm using <code>LEFT(ReturnDate,4)</code>.</p>
  
  <p>It all seem OK so far, but I need the list to show Year, City and the complete number of returns for that city, like:</p>
  
  <pre><code>YEAR       CITY        QUANTITY
  2011       London      300
  2011       Stockholm   40
  2012       London      250
  </code></pre>
  
  <p>Now, I'm not getting:</p>
  
  <pre><code>YEAR       CITY        QUANTITY
  2011       London      200
  2011       London      100
  2011       Stockholm   30
  2011       Stockholm   10
  2012       London      250
  </code></pre>
  
  <p>This is what I've come up with so far:</p>
  
  <pre><code> SELECT LEFT(ReturnDate,4) AS Year, City, COUNT(ReturnDate) AS Quantity 
   FROM Member
   GROUP BY ReturnDate, City
  </code></pre>