操作account表，查询客户不是推荐人的数据，下列sql语句正确的是：( )
select real_name from account o where not exists ( select 1 from account i where o.id = i.recommender_id);
select real_name from account o where not exists ( select real_name from account i where o.id = i.recommender_id);
select real_name from account o where not in ( select 1 from account i where o.id = i.recommender_id);
select real_name from account o where not in ( select real_name from account i where o.id = i.recommender_id);
