title: add column to table and set value based on the value of another column
body: <p>I have encountered the following issue: I have a table with several columns, now I need to add a new column to this table and then fill it with the encrypted (md5) value of another column.</p>
  
  <p>1)</p>
  
  <pre><code>ALTER TABLE myTable ADD md5_city VARCHAR(255);
  </code></pre>
  
  <p>2)</p>
  
  <pre><code>"UPDATE myTable SET md5_city = " . md5($cityValue) . ";"
  </code></pre>
  
  <p>Is there a better way to do this?</p>