使用find的Rails SQL查询

使用find的Rails SQL查询

简单方法：

ids = LevelsQuestion.all(:select => "question_id",         :conditions => "level_id = 15").collect(&:question_id)Question.all(:select => "id, name", :conditions => ["id not in (?)", ids])

一q：

Question.all(:select => "id, name",:conditions => ["id not in (select question_id from levels_questions where level_id=15)"])