title: INSERT INTO ... VALUES () when not exists
body: <p>I have insert:</p>
  <pre><code>INSERT INTO barrier
  (barrier_id,
   usage_id,
   type_id,
   currency_id,
   modified_date,
   version_nr)
  VALUES (barrier_seq.nextval,
          (SELECT usage_id
           FROM usages
           WHERE id =
                 (SELECT id
                  FROM products
                  WHERE identifier =
                        (SELECT identifier
                         FROM identifiers
                         WHERE type_id =
                               (SELECT type_id
                                FROM types
                                WHERE NAME = 'New product')
                           AND LOCATION = 'USA')
                    AND status = 'DONE')),
          (SELECT type_id FROM types WHERE name = 'My name'),
          5,
          CURRENT_TIMESTAMP,
          3);
  </code></pre>
  <p>I know that I can use <code>where not exists</code> when there is <code>SELECT</code> in <code>INSERT</code> instead of <code>VALUES()</code> (<a href="https://stackoverflow.com/questions/10824764/oracle-insert-if-not-exists-statement">Oracle insert if not exists statement</a>). Is it somehow possible in this case without changing this <code>INSERT ... VALUES()</code> into <code>INSERT... SELECT</code>?</p>