title: PHP PDO - What do $dbh and $sth stand for?
body: <p>In PDO examples I often find the acronyms <code>$dbh</code> and <code>$sth</code> used.  I suppose <code>$dbh</code> stands for "database handle" - correct?  What about <code>$sth</code>?  "Statement handle"?</p>
  
  <p>Are there good reasons to use the above instead of <code>$db_connection</code> and <code>$query</code> (or other as appropriate)?</p>