title: Return deafult value in SQL select statment searched value is not found
body: <p>I need to return default value in Select statement when WHERE clause is not met.
  So basically, this query returns valid guid:</p>
  <pre><code>SELECT COALESCE(w.guid , gen_random_uuid()) as guid
          FROM MyTable w
          WHERE w.id = 108
          AND w.company IN (27);
  </code></pre>
  <p>But this doesn't find id 109, so it should generate new random uuid:</p>
  <pre><code>SELECT COALESCE(w.guid , gen_random_uuid()) as guid
          FROM MyTable w
          WHERE w.id = 109
          AND w.company IN (27);
  </code></pre>
  <p>But instead it returns nothing. How I can solve this?</p>