title: CONCAT in sql developer
body: <p>it does not runing,please show me where I have a mistake?</p>
  
  <pre><code>SELECT CONCAT(FIRST_NAME,',',LAST_NAME) as full_name FROM EMPLOYEES;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/iztJQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iztJQ.png" alt="enter image description here"></a></p>