More usage of dbm::is_result($r) instead of count($r):

More usage of dbm::is_result($r) instead of count($r):
- count() returns very different results and never a boolean (not even false on
  error condition).
- therefore you should NOT use it in boolean expressions. This still *can* be
  done in PHP because of its lazyness. But it is discouraged if it comes to
  more clean code.

Signed-off-by: Roland Häder <roland@mxchange.org>