Aug 15 2009
Designing Databases
When we are designing any database, we need to produce a conceptual data model. We use the following terms:
- Entity – any item that is of interest, e.g. stock, customers, or suppliers.
- Attributes – any property of an entity, e.g. supplier’s address.
- Relationships – any association between two entities.
There are three kinds of relationships:
- One-to-one – a husband and wife.
- One-to-many – a doctor and patients. Each patient has one doctor.
- Many-to-many – albums to singers.
We can show these as entity relationship diagrams.