title: change all existing collation of columns
body: <p>I have a table which some of its columns has collation of utf8_bin. But I need to change them to utf8_unicode_ci. 
  I know this query for do it:</p>
  
  <pre><code>ALTER TABLE  `shn_sho_cities` CHANGE  `city_name`  `city_name` VARCHAR( 100 ) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL ;
  </code></pre>
  
  <p>but as I want change all columns which have utf8_bin instead of writing a query for each column. 
  Is there any way which I could do this?</p>