title: Fix incorrectly encoded JSON data
body: <p>I was trying to fix some data up for a client and have instead broken it further by json_encoding already json_encoded data and ending up with a database filled with unusable strings. </p>
  
  <p>One such broken string looks like this</p>
  
  <pre><code>"[{\"datum_von\":\"2012\",\"datum_bis\":\"2012\",\"organisation\":\"A s.r.o., školící středisko pro vrcholný management\",\"hauptfaecher\":\"Top management\"},{\"datum_von\":\"2011\",\"datum_bis\":\"2011\",\"organisation\":\"Goethe Institut\",\"hauptfaecher\":\"Německý jazyk\r\n\"}]"
  </code></pre>
  
  <p>Any tips on fixing this would be appreciated.</p>