title: format table with varchar date format to date mysql
body: <p>I have a database with multiple tables using date fields.</p>
  
  <p>Some of them have this format as <code>varchar(10)</code> <code>dd-mm-yyyy</code> and other have a mix of <code>dd-mm-yyyy</code> and <code>yyyy-mm-dd</code>.</p>
  
  <p>I tried changing the format of the fields to <code>DATE</code>, however, everything in <code>dd-mm-yyyy</code> turn into <code>0000-00-00</code></p>
  
  <p><strong>There is a correct way turn all varchars as date type and only dd-mm-yyyy into DATE format in the tale with mixed date formats before change the field type?</strong></p>
  
  <pre><code>date
  --------
  01-12-2015 *** change this
  05-11-2016 *** this
  01-04-2016 ***  and this
  2016-05-11 +++ and keep the ones on this format
  </code></pre>