title: Update json field value to lower case in Postgres
body: <p>I have a table which includes a json field. One of the key have mixed case values and I want to convert them to lower case. I have tried a few methods to do that,  but nothing works and raising explicit cast issues.</p>
  
  <pre><code>UPDATE table SET data = LOWER( CAST (data AS json)) WHERE id=123;
  </code></pre>
  
  <p>Above query raised the following error.</p>
  
  <blockquote>
    <p>No function matches the given name and argument types. You might need
    to add explicit type casts.</p>
  </blockquote>
  
  <ul>
  <li>I have also tried to update particular key but that also raised the same kind of error. </li>
  <li>I am not sure if PostgreSQL allowed such kind of operation on json data </li>
  </ul>