title: Are sub-SELECT's in SELECT and FROM clauses standard-compliant?
body: <p>The title pretty much says it all.  Under "standard-compliant" SQL I mean SQL constructs allowed in any of SQL standards.</p>
  
  <p>I looked through the "Understanding SQL" book, but it mentions subqueries only inside <code>WHERE</code>, <code>GROUP BY</code>, <code>HAVING</code> etc. clauses, not <code>SELECT</code> and <code>FROM</code> (or maybe I'm missing something).</p>
  
  <p>I know MS SQL allows sub-SELECT's in <code>SELECT</code> and <code>FROM</code>.  I would like to know if it is a standard behavior.  Or maybe it isn't standard, but is now implemented in major SQL databases (I have very little experience with DB's other than MS SQL)?</p>