So you can use something like this:
$query = $db->select();
$query->from(\'pages\', array(\'url\'));
echo $query->__toString();
to
Use Zend_Db_Profiler to capture and report SQL statements:
$db->getProfiler()->setEnabled(true);
$db->update( ... );
print $db->getProfiler()->getLastQueryProfile()->getQuery();
print_r($db->getProfiler()->getLastQueryProfile()->getQueryParams());
$db->getProfiler()->setEnabled(false);
Remember to turn the profiler off if you don't need it! I talked to one fellow who thought he had a memory leak, but it was the profiler instantiating a few PHP objects for each of the millions of SQL queries he was running.
PS: You should use quoteInto() in that query:
$n = $db->update('pages', $data, $db->quoteInto("url = ?", $content));