참고 http://www.javamakeuse.com/2015/03/tutorial-hibernate-4-subselect-fetching.html https://www.mkyong.com/hibernate/hibernate-fetching-strategies-examples/ https://stackoverflow.com/questions/32984799/fetchmode-join-vs-subselect http://kwonnam.pe.kr/wiki/java/jpa/one-to-one https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-hibernate/ https://stackoverflow.com/ques..