I used '_portal_' prefix for my MySQL tables, and have Error while fetch records from tables.

this is the Doctrine_Query string :

SELECT 
  _.gid AS ___gid, 
  _.name AS ___name, 
  _.email AS ___email, 
  _.comment AS ___comment, 
  _.tstamp AS ___tstamp, 
  _.status AS ___status 
FROM 
 _portal_guestbook _ 
WHERE 
 _.status = 1

below the snapshot from the exception:

Call to a member function getFieldName() on a non-object in /var/www/portal/lib/doctrine/Doctrine/Hydrator.php on line 293

call stack:
...
7	0.2288	12997676	Doctrine_Hydrator->hydrateResultSet( )	../Abstract.php:953
8	0.2319	13185000	Doctrine_Hydrator->_gatherRowData( )	../Hydrator.php:119

in my search,the error starting in Doctrine_Hydrator line 287 :

$e = explode('__', $key);

while tablename's first character is underscore '_' and Doctrine_Query use it as table alias; it makes ambiguation. i try to use table alias $record->getTable()->createQuery('p'); but not work.