Mapping obj to relational db strategies

1. Table per concrete class - buang semua hubungan polymorphism and inheritance dari domain model

2. Table per class hierarchy- wujudkan poly dengan cara meng normalkan hubungan model dan gunakan jenis diskriminasi column utk hold type info


3. table per subclass - represent "is a" (inherintance) r/ships as "has a" (foreign key) relationships