title: Change varchar m/d/yy to yyyy-mm-dd
body: <p>I have a varchar(9) column with data that is in the form m/d/yy.  I want to convert it to yyyy-mm-dd.  I can select all the values and view my changes using this query, </p>
  
  <pre class="lang-sql prettyprint-override"><code>SELECT STR_TO_DATE(date_new,'%m/%d/%Y') as date
    FROM july
  </code></pre>
  
  <p>My problem is how to update all those values in that column.  I tried using this query, messes up all the dates.</p>
  
  <pre class="lang-sql prettyprint-override"><code>UPDATE july
     SET date_new = str_to_date(date_new, '%d-%m-%Y' );
  </code></pre>
  
  <p>Any help would be gladly accepted! </p>
  
  <p>Thank you in advance. :)</p>