title: join of value lists in postgres
body: <p>I need to join two value lists in postgres.
  I tried the following but it does not work;</p>
  <pre><code>select a.*,b.* from (values('a'),('b')) as a join (values('1'),('2'),('3')) as b ;
  </code></pre>
  <p>What should I write instead ;
  The result should be a table of 6 values.</p>