title: Oracle 12c: WHERE NOT vs WHERE ... OR
body: <p>I need to select rows where <strong>RN=1</strong> or <strong>ID is NULL</strong>.
  Which condition is more efficient and fast?</p>
  <pre><code>WHERE id IS NULL OR RN=1
  </code></pre>
  <p>vs</p>
  <pre><code>WHERE NOT (id IS NOT NULL AND RN &gt;1)
  </code></pre>