android room db start

1. room db

• implement
  

2. MainDatabase

3. MemoEntity

• primarykey 여러개

@Entitiy(primaryKeys = {"id", "memo"})

• ForeignKey

@Entitiy(foreignKeys = {@ForeignKey(
    			entity = Project.class,
            		parentColumns = "id",
                	childColumns = "id",
                	onDelete = ForeignKey.CASCADE)}
)

• indexing

@Entity(indices = {
    		@Index(name = "id_index", value= {"id"})}
)

• 개체간 관계
  • 일대일
    
• 일대다
  

4. MemoDAO

5. RoomActivity

6. 실행결과

view > tool windows > database inspector