title: Oracle SQL Developer - Database Copy/Database Diff grayed out
body: <p>In SQL Developer version 19.2, when i pinpoint to "Tools", options "Database Copy" and "Database Diff" are grayed out. 
  How to enable them? </p>
  
  <p><a href="https://i.stack.imgur.com/H19rJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/H19rJ.png" alt="enter image description here"></a></p>