Discuss in detail about data modeling.
- Data modelling makes use of the ERD.
- Consists of three interconnected information.
The data object.
Attributes.
Relationships.
Cardinality and Modality
- Cardinality means the specification of the number of occurrences of one object that can be linked to the number of occurrences of another object.
- One-to-one cardinality.
- One-to-many cardinality.
- Many-to-Many cardinality.
- Modality of a relation is 0 when no explicit relationship or relation is optional.
- Modality is 1 when occurrence of relationship is mandatory.
Entity/Relationship Diagrams
Data Objects.
Attributes.
Relationships.
Various type indicators.