Web Framework)Entity RelationShip

1)Entity RelationShip types = @OneToOne , @OneToMany, @ManyToOne, @ManyToMany

2)direction : bidirectional, unidirectional

3)Entity Relation Attributes

1: CascadeType: 연관된 것도 동일 적용 할 것 인지 //부모쪽에 주로 넣기
ALL, PERSIST,MERGE,REMOVE,REFRESH

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)

2: FetchType : 연관된 것도 로드할 것 인지 LAZY=로드 적용 x , EAGER= 로드 동일 적용

@OneToMany, @ManyToMany = FetchType.LAZY

@OneToOne, @ManyToOne= FetchType.EAGER

4)OneToMany Unidirectional

@ManyToOne(cascade=CascadeType.ALL)

@JoinColumn(name="category_id")

private Category category

-외래키는 Many(child)쪽에 둘 것 parent=One 쪽, childe= Many쪽

-@ManyToOne =Many 쪽이고 child구나라고 hibernate가 알려줌

-@joinColumn = join할때 사용하는 column은 무엇인지

5)OneToMany bidirectional

@OneToMany (mappedBy = "category", cascade= Cascade=CascadeType.ALL, fetch=FetchType.LAZY

private Set products;

@ManyToOne

@JoinColumn(name="category_id")

private Category category;

-mappedBy : child class에 represent한 parent가 무엇인지One , @OneToMany, @ManyToOne, @ManyToMany

6)direction : bidirectional, unidirectional

7)Entity Relation Attributes

1: CascadeType: 연관된 것도 동일 적용 할 것 인지 //부모쪽에 주로 넣기



 ALL, PERSIST,MERGE,REMOVE,REFRESH

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)

2: FetchType : 연관된 것도 로드할 것 인지 LAZY=로드 적용 x , EAGER= 로드 동일 적용

@OneToMany, @ManyToMany = FetchType.LAZY

@OneToOne, @ManyToOne= FetchType.EAGER

4)OneToMany Unidirectional

@ManyToOne(cascade=CascadeType.ALL)

@JoinColumn(name="category_id")

private Category category

-외래키는 Many(child)쪽에 둘 것 parent=One 쪽, childe= Many쪽

-@ManyToOne =Many 쪽이고 child구나라고 hibernate가 알려줌

-@joinColumn = join할때 사용하는 column은 무엇인지

5)OneToMany bidirectional

@OneToMany (mappedBy = "category", cascade= Cascade=CascadeType.ALL, fetch=FetchType.LAZY

private Set products;

@ManyToOne

@JoinColumn(name="category_id")

private Category category;

-mappedBy : child class에 represent한 parent가 무엇인지

6)OneToOne Unidirectional

외래키 가진 One쪽 -License

@OneToOne(optional =false, cascade=CascadeType.ALL)

@JoinColumn(unique=true, name="person_id")

private Person person;

license.setPerson(person)

7)OneToOne bidirectional

license.setPerson(person);

person.setLicense(license);

8)ManyToMany unidirectional -> jointable 사용

각 테이블의 기본키를 가지는 jointable

@ManyToMany(cascade= CascadeType.ALL

@JoinTable(name ="author_book", joinColumns = {@JoinColumn(name = "book_id")}, inverseJoinColumns = {@JoinColumn(name ="author_id")})

private Set authors;