About

group (or grouping) refers to the fact of putting things (elements) together in a container. This is a one-to-many relationship.

In data modeling, you group:

• attributes in:
  • an entity
  • a relationship
• entity in:
  • an entity set (collection) - aggregation relationship
  • a namespace (tree) - hierarchy relationship
  • a assembly - composition relationship
• relationship in:
  • an relationship set (collection) - aggregation relationship
  • a namespace (tree) - hierarchy relationship

Implementation

Grouping is represented in a relational model by a one-to-many relationship (ie foreign key constraint)