💡 The slides for this lecture can be found here.
Abstraction is the process of representing essential features without including the background features.
Data is the foundation of an information system.
- One way of modelling data is an Entity Relationship Diagram (ERD).
Relational Data Modelling
Relational Data Modelling is a classic form of modelling data in which every object and entity relates to each other using a set of rules and keys.
- One example of a relational database is SQL.
There are a few key parts of an ERD.
- An entity is a 'thing' that can occur.
- An instance is a specific occurrence of the entity.
- An event is an entity what occurs as specific times, or is time-based.
- An object is an entity with no tie to time.
- An attribute is something that an entity is keeping track of.
- A cardinality describes how two entities relate to each other.
The different cardinalities.