title: Mysql/Maridb Update is not working
body: <p>Suppose a table contains data like </p>
  
  <pre><code>MariaDB [c]&gt; select * from t2;
  +-----+
  | abc |
  +-----+
  |   1 |
  |   3 |
  |   5 |
  +-----+
  </code></pre>
  
  <p>Suppose my update command is </p>
  
  <pre><code>MariaDB [c]&gt; update t2 set abc = abc+2;
  </code></pre>
  
  <p>It give following error</p>
  
  <pre><code>ERROR 1062 (23000): Duplicate entry '3' for key 'PRIMARY'
  </code></pre>
  
  <p>While the above command works fine in oracle 10g, Is it some kind of bug or what?</p>