title: MySql Sorting columns from 2 or more tables by date
body: <p>I have the following tables:</p>
  
  <pre><code>comments:
  id   /   comments    /   date
  1        comment1     1389986953
  2        comment2     1389986935
  
  
  topics:
  id   /   topics    /   date
  1        topic1      1389986930
  2        topic2      1389986940
  </code></pre>
  
  <p>How can i select all the rows from both tables and sort them by the date?
  so it will look something like:</p>
  
  <pre><code>topic1
  comment2
  topic2
  comment1
  </code></pre>