title: Remove all characters after a specific character in PL/SQL
body: <p>How do I get a substring from this example value: </p>
  
  <pre><code> john.abc_1234
  </code></pre>
  
  <p>I want it to return <code>john.abc</code>.So basically we need to remove all the information after <code>_</code>. </p>
  
  <p>More examples: 1234_abc</p>