title: Prevent error when dropping not existing sequences, creating existing users
body: <p>I have a bunch of sql scripts that create / drop sequences, users and other objects. I'm running these scripts through liquibase, but they fail because oracle complains when I try to drop a non existing sequence, or create an existing user.</p>
  
  <p>Is there an oracle way to prevent errors from happening? </p>
  
  <p>Something of the sort </p>
  
  <blockquote>
    <p>Create User / Sequence if not exists</p>
    
    <p>Drop User/ Secuence if exists</p>
  </blockquote>
  
  <p>As far as I know, I have these options:</p>
  
  <ul>
  <li>Write a plsql script</li>
  <li>Use liquibase contexts.</li>
  <li>Use liquibase preconditions, but this would mean too much work.</li>
  </ul>
  
  <p>Any thoughts / ideas will be greatly appreciated.</p>