select  n_code from table1(表名) where  n_orgid is not null
                group by n_code,n_orgid
                         having count(n_orgid)>1
 

select *  from 
        (select count(n_code) as c  from table1(表名) 
                group by n_code,n_orgid) as tt
                                 where c>1;