title: How to select multiple rows filled with constants?
body: <p>Selecting constants without referring to a table is perfectly legal in an SQL statement:</p>
  
  <pre><code>SELECT 1, 2, 3
  </code></pre>
  
  <p>The result set that the latter returns is a single row containing the values. I was wondering if there is a way to select multiple rows at once using a constant expression, something kind of:</p>
  
  <pre><code>SELECT ((1, 2, 3), (4, 5, 6), (7, 8, 9))
  </code></pre>
  
  <p>I would want something like the above that works and returns a result set with 3 rows and 3 columns.</p>