AP
Size: a a a
AP
AP
LD
AP
LD
AP
PK
book -> volume -> page
book
- id
volumes:
- id
- book_id
pages
- id
- volume_id
book has many volume
volume has many page
volume belongs to book
page belongs to volume
PK
🎃
lv
PK
PK
🎃
lv
PK
$table->foreignId('volume_id')->constrained('volumes')->onDelete('cascade');
PK
AB