title: extract current date and current year from varchar on MySQL
body: <p>How I make to get back login and nb_match over the year and the current month of my table? </p>
  
  <p>this is my query for all matching without the month ....</p>
  
  <pre class="lang-sql prettyprint-override"><code>SELECT login, SUM(column1) 
  FROM 'my_table'
  NATURAL JOIN 'join_table' 
  GROUP BY login
  </code></pre>
  
  <p>(<code>at_limitation_admin</code> is the natural join on 'login' column). 'month' is varchar column. (example 2009/03)</p>