title: PLSQL: using subquery in if-statement error PLS-00405
body: <p>I'm getting error pls-00405 when I try to run this code:</p>
  
  <pre><code>BEGIN
    IF :P10_KAART_CODE IN (SELECT KAART_CODE FROM CADEAUKAART) THEN
       RETURN TRUE;
    ELSE
      RETURN FALSE;
    END IF;
  END;
  </code></pre>
  
  <p>There are some similar questions about this but couldn't find a solution for this simple code. Is there another way of writing this without facing a error?</p>