* FIX: the query introduced by commit 93d30e4

the query won't work if the database used is postgres due to
type mistmacth in the where condition: lime_question_attributes.value=1

Since lime_question_attributes.value is of type "text" it needs to
be compared against strings rather then numbers.

The error reported by postgres is:

ERROR:  operator does not exist: text = integer at character 238
No operator matches the given name and argument type(s). You might
need to add explicit type casts.

application/helpers/frontend_helper.php

@@ -1218,7 +1218,7 @@ function buildsurveysession($surveyid,$preview=false)
     ." JOIN {{question_attributes}} ON {{question_attributes}}.qid = {{questions}}.qid"
     ." WHERE {{questions}}.sid=".$surveyid."\n"
     ." AND {{question_attributes}}.attribute='hidden'"
-    ." AND {{question_attributes}}.value=1"
+    ." AND {{question_attributes}}.value='1'"
     ." AND {{questions}}.language='".App()->getLanguage()."'\n"
     ." AND {{questions}}.parent_qid=0\n";
     $totalHiddenQuestions = Yii::app()->db->createCommand($sQuery)->queryScalar();