title: Nested NULLIF (Assign value of a column to null if (condition A) or (condition B)) in SQL without CASE
body: <p>I have a column C1 with values that can either be 'values' or 'empty' or 'N/A'.</p>
  <pre><code>|  C1 |
  -------
  |     |
  | N/A |
  |apple|
  </code></pre>
  <p>I want to SELECT column C1 in a way that it converts empty values and N/A to NULL using NULLIF.</p>
  <pre><code>|  C1 |
  -------
  |NULL |
  |NULL |
  |apple|
  </code></pre>
  <p>We can do <code>NULLIF(C1, '')</code> which gives NULL if the column value is empty.</p>
  <p>We can also use CASE and implement both case that way but I want to know if there is a way to use NULLIF for it and if so, how? (or any way other than CASE)</p>
  <p>Something like <code>NULLIF(C1, '' OR 'N/A')</code></p>
  <p>Thanks in advance.</p>