Introduction to Object-Relational Databases | Realcode4you

realcode4you · 2023-04-06T10:11:51.595Z

Table of Content • Introducing UML Class Diagram • Key features of Object Relational Data Model (E.g. SQL:2003 object model; LOBs, UDTs, OID, Multisets) Introduction to UML Class UML Class Notation UML Association vs Composition vs Aggregation Association UML Aggregation Example UML Composition Example • Unidirectional Association: An object might store another object in a field. For example, people own books, which might be modeled by an owns field in Person objects. • However, a book might be owned by a very large number of people, so the reverse direction might not be modeled. The *'s in the figure indicate that a book might be owned any number of people, and that a person can own any number of books. • Bidirectional Association: Two objects might store each other in fields. For example, in addition to a Person object listing all the books that the person owns, a Book object might list all the people that own it.

Table of Content

Introducing UML Class Diagram
Key features of Object Relational Data Model (E.g. SQL:2003 object model; LOBs, UDTs, OID, Multisets)

Introduction to UML Class

UML Class Notation

UML Association vs Composition vs Aggregation

Association

UML Aggregation Example

UML Composition Example

Unidirectional Association: An object might store another object in a field. For example, people own books, which might be modeled by an owns field in Person objects.
However, a book might be owned by a very large number of people, so the reverse direction might not be modeled. The *'s in the figure indicate that a book might be owned any number of people, and that a person can own any number of books.

Bidirectional Association: Two objects might store each other in fields. For example, in addition to a Person object listing all the books that the person owns, a Book object might list all the people that own it.

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