Explain in detail about data modelling.

• Data modeling makes use of the ERD.
• Having of 3 interrelated information.

The data object.

Attributes.

 Relationships.

Cardinality and Modality

• Cardinality is the specification of the number of occurrences of one object that can be related 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 if there is no explicit relationship or relation is optional.
• Modality is 1 if an occurrence of relationship is mandatory.

Entity/Relationship Diagrams

• Components are

Data Objects.

Attributes.

Relationships.

Several type indicators.