ORA-01427 에러 발생시

select * from qna_item where auth_userid=(select userid from hr_user_detl
where CSTM_FIELD6=200227);

ORA-01427 : single-row subquery returns more than one row
(서브쿼리에 의해 리턴된 데이터가 한건 이상 이다!)

해결법
select * from qna_item where auth_userid in
(select userid from hr_user_detl where CSTM_FIELD6=200227);
= select * from qna_item k, hr_user_detl h where h.userid=k.auth_userid and cstm_field6=200227;