title: Update all values of a column to lowercase
body: <p>Lets say I have something like this</p>
  
  <pre><code>uid    tag
  1      HeLLo
  2      heLLO
  3      HELLO
  4      hello
  </code></pre>
  
  <p>How can I update all values in the "tag" column to:</p>
  
  <pre><code>uid    tag
  1      hello 
  2      hello 
  3      hello 
  4      hello 
  </code></pre>
  
  <p>using MySQL?</p>