title: how to alter table column data type
body: <p>I've the following column</p>
  
  <pre><code>hits text NOT NULL
  </code></pre>
  
  <p>and want to alter it to </p>
  
  <pre><code>hits bigint(20) unsigned NOT NULL default '0'
  </code></pre>
  
  <p>how to use ALTER TABLE commands to do this change ! ~ thanks</p>