越來越糟糕=w=/

@Entity

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)

如果model無法自動取得, 需在spring導入程式加上annotation提示系統自動載入, 若model在主module下則無須此動作

@EntityScan("testing.spring.model") 

                        ^^^^^^^^^^^^^  model 的package位置

one side set to map by join column and inverse join column

@ManyToMany
    @JoinTable(name="A_B",joinColumns= @JoinColumn(name="B_id"), inverseJoinColumns=@JoinColumn(name = "A_id"))

another side set to map by variable name

@ManyToMany(mappedBy = "As")

repository --> add standard spring CRUD function

public interface xxxRepository extends CrudRepository<type of data model, type of id>{
    
}

H2資料庫來源自動設定 add at application.properties
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=