Basic ER Modeling Constructs

These flashcards cover key concepts related to Basic ER Modeling Constructs and definitions pertinent to understand relational databases.

Entity Type

The form of the objects, events, or things we want to capture data about, defined by a name and its attributes, analogous to a table.

Entity Instance

An example of the objects, events, or things that represent data, defined by its values for the attributes of its entity type, analogous to a row.

Attributes

Characteristics that define an entity type and can include various types like primary key attributes, foreign key attributes, and composite attributes.

Primary Key Attributes

Attributes that uniquely identify each entity instance in a table.

Foreign Key Attributes

Attributes that establish a link between two tables, referring to the primary key in another table.

Multivalued Attributes

Attributes that can have multiple values for a single entity instance.

Relationship Degree

The number of entity types that can participate simultaneously in a relationship; e.g. unary, binary, or ternary.

Cardinality

The number of instances of an entity that may participate in a relationship.

Specialization

The process of creating subtypes from a general entity by focusing on attributes that only apply to certain instances.

Generalization

The process of combining multiple entities with common attributes into a more general entity.

Referential Integrity

A rule that ensures that a foreign key must either refer to an existing primary key or be NULL.

Entity Integrity

A rule that requires that primary key attributes cannot be NULL and must be unique for every row in a table.

Relational Schema

The structure that defines how data is organized in a relational database, including tables, fields, and relationships.

Composite Attributes

Attributes that can be divided into smaller sub-parts, which represent more basic attributes.

Derived Attributes

Attributes that can be calculated or derived from other data rather than stored directly.