我希望使用find在rails控制器中编写这个SQL查询：
select id,name from questions where id not in (select question_id from levels_questions where level_id=15)
解决方法
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])
一枪：@H_403_6@
Question.all(:select => "id,:conditions => ["id not in (select question_id from levels_questions where level_id=15)"])
