Final answer:
In ERDs, a composite entity is shown as a rectangle and solves many-to-many relationships by containing primary keys from each related entity. Using crow's foot notation, these relationships are depicted with fan-like symbols indicating one-to-many connections, and in a composite entity's case, it connects both related entities.
Step-by-step explanation:
In an Entity-Relationship Diagram (ERD), a composite entity, sometimes referred to as a bridge entity, is represented by a rectangle and is used to resolve many-to-many relationships between two entities. It functions by holding the primary keys from each of the entities involved in the many-to-many relationship, which becomes a compound primary key for the composite entity.
The crow's foot notation in ERDs visually represents relationships between entities. A crow's foot, which resembles a bird's foot or a fan of several lines, is placed at the end of the line connected to the entity that can have multiple associated records. For example, a single customer (represented with a single line) may have multiple orders (represented by the crow's foot), indicating a "one-to-many" relationship. In a composite entity situation, the crow's foot would be used on both sides of the composite entity to signify the many parts of the many-to-many relationship that is being resolved.