title: Inserting in mySQL a JSON encoded value with special chars fails
body: <p>I am trying to execute this query with PDO:</p>
  
  <pre><code>UPDATE categories
  SET keywords = '{"bg":["keyword1","\u0431\u044a\u043b\u0433\u0430\u0440\u0441\u043a\u0438 "]}'
  WHERE id = 4;
  </code></pre>
  
  <p>The problem is that it seems to record the hex value without the backslashes ("\"). It does show up without the backslashes in my app but also in PHPMyAdmin.</p>
  
  <p>I use exec() on this query, and I have tried it with this full-text query, without any dynamic/transformed variables. The PDO parameters are as follow:</p>
  
  <pre><code>PDO::ATTR_ERRMODE =&gt; PDO::ERRMODE_EXCEPTION,
  PDO::MYSQL_ATTR_USE_BUFFERED_QUERY =&gt; true,
  PDO::MYSQL_ATTR_INIT_COMMAND =&gt; "SET NAMES utf8"
  </code></pre>
  
  <p>Can someone explain me what is happening here? Thanks!</p>
  
  <p>UPDATE: I have executed this exact query from mysql's CLI, then displayed it there, and the problem is the same: all the backslashes have disappeared. So it doesn't seem the problem has anything to do with PDO, but with MySQL - or me! My version is 5.1.53</p>