Selecting a Design Strategy

Object Persistence Formats

What are they

Selecting the right format

Relational Databases (RDBs)

RDB Table/Entities

• Tables are also known as entities

• Entities names must start with a capital letter

• They are inter-related using the key-matching mechanism

• Each entity contains a number of attributes, starts with lower case later

• Each entity has a one unique identifier called a primary key

• A foreign key is a entities attribute that refers to another entities primary key

Entity Relationship Diagram (ERD)

Data types

Classes to ERD

1. Classes usually mapped to a table with same attributes

2. Class associations mapped to ERD relationships

3. Class generalisations mapped to ERD tables

4. Leave methods

Mapping Associations

Example

Mapping Generalisation SUPER CLASS METHOD

Example

Mapping Generalisation MULTIPLE CLASS METHOD

Example