[DataBase] 각 DataBase 각각 컬럼별 연결

• ex) < Faqboard라는 엔티티를 만들 때, Member에 있는 id를 가져오고 싶은 경우 >
  
  - Faqboard에 필드 생성시 이를 추가
  
      @ManyToOne
      @JoinColumn(name = "member_id")
      private Member member;
  ->
  create table aaa.FAQBOARD
  (
      BOARD_ID           bigint       not null  primary key,
      CONTENT            varchar(255) null,
      QUESTION_ANSWER_ID bigint       null,
      READ_COUNT         bigint       null,
      SUBJECT            varchar(255) null,
      WRITE_DATE         varchar(255) null,
      MEMBER_ID          bigint       null,
      constraint FK2dsfdsfs8fs8fgsifhs9fshf9sde
          foreign key (MEMBER_ID) references aaa.MEMBER(ID)
  );

 

 

• ex) <Faqboard가 미답변 테이블일때 QuestionAnswer인 답변 테이블과 연결하여 내용 출력하고, 
         faqboardId에 Faqboard테이블의 primary키 아이디를 출력해주고 싶은 경우>
  
  SELECT *
  from aaa.FAQBOARD f inner join aaa.QUESTION_ANSWER q 
  on q.id = f.question_answer_id 
  where f.question_answer_id > 0
  
  -> 미답변 테이블(FAQBOARD)의 questionAnserId가 0보다 큰수 일때 
      답변 테이블(QuestionAnswer)의 id(primary)와 연결
  
  그 후 ,
  
  답변 테이블(QuestionAnswer)의 faqboardId에 미답변 테이블(FAQBOARD)의 boardId 를 builder 해줌