متعدد إلى متعدد وكيانات الربط

في هذا الدرس

know when @ManyToMany is enough and when to model the link.

الموضوعات المخطط لها

• @ManyToMany uses a hidden join table with only the two foreign keys.
• It cannot hold extra data (quantity, date, price at the time).
• When the link has data, create an entity for it (OrderLine links Order and Product with quantity and price).
• Each side then has a plain @OneToMany to the join entity.
• Prefer explicit join entities from the start in real systems.