Description:
- Every row of that table cannot exist without depends on prior existence of another strong entity
ID-dependent weak entity
- Has a composite identifier:
- the first part of the identifier is primary key for the strong entity
- the second part of the identifier is primary key for weak entity itself
- Example: A book has many chapter
Non-ID-dependent weak entity
- Doesn’t include the primary key of the parent’s entity, it is instead foreign key
- It must have a relationship with the parent entity in order to be fully identified.