4.5

Supertype

A general entity type that can have one or more subtypes, highlighting subsets of data with different attributes or relationships.

Subtype

A specialized version of a supertype, inheriting its attributes and potentially adding new ones, used to clarify database semantics.

Cardinality

The relationship between entities in terms of the number of instances that can be associated with each other.

Weak Entity

An entity that cannot be uniquely identified by its attributes alone and relies on a strong entity for its identification.

Optional Attributes

Attributes that may or may not be present for an entity instance, offering flexibility in entity definitions.

Partition Attribute

An attribute that specifies which subtype an instance of a supertype belongs to, indicating the relationships tied to each subtype.

Entity Instance

A specific occurrence of an entity, which can exist in multiple subtypes across different partitions.

Conceptual Design

The initial steps in database design that involve discovering entities, relationships, and attributes before creating the data model.