Converting Entity Relationship Models to Relational Models

Flashcards covering key concepts and conversion rules for transforming Entity Relationship Models into Relational Models, including different types of relationships and special cases.

Database Development Lifecycle

A structured process for developing databases, including identifying problems, gathering requirements, creating conceptual and logical models, optimizing, and implementing.

Conceptual Data Model

An abstract model representing the problem domain, typically using an Entity Relationship Model (ERM).

Logical Data Model

A more detailed representation of the data structure, typically using a Relational Model, derived from the conceptual model.

Entity (Conceptual Model)

A real-world object or concept in the Entity Relationship Model, which converts to a 'Relation' in the Logical Model and a 'Table' in the Physical Model.

Relation (Logical Model)

A tabular structure in the Relational Model, derived from an Entity in the Conceptual Model, and implemented as a 'Table' in the Physical Model.

Attribute (Conceptual/Logical Model)

A characteristic or property of an Entity or Relation, which converts to a 'Column' in the Physical Model.

Identifier (Conceptual Model)

An attribute or set of attributes that uniquely identifies an Entity, which converts to a 'Key' in the Logical Model and a 'Primary Key' in the Physical Model.

Key (Logical Model)

An attribute or set of attributes that uniquely identifies a Tuple (row) in a Relation, becoming a 'Primary Key' in the Physical Model.

Foreign Key (FK)

An attribute in one relation that refers to the Primary Key of another relation, used to establish relationships between tables.

One-To-Many Relationship Conversion

The process where the Key from the 'One' side of the relationship is copied as a Foreign Key to the relation on the 'Many' side.

One-To-One Relationship Conversion

The process where a Foreign Key is placed on one of the sides only, typically copying the Key from one relation to another related relation.

Many-To-Many Relationship Conversion

The process of creating a new 'Intersection Relation' that combines the names of both entities and includes the Keys from both sides as Foreign Keys, forming a Composite Key for the new relation.

Intersection Relation

A new relation created to resolve a Many-To-Many relationship, containing the Foreign Keys from both participating entities, which together form its Composite Key.

Composite Key

A key that consists of two or more attributes that together uniquely identify a row in a relation.

ID Dependent Entity

An entity whose identifier (and thus its primary key in the relational model) depends on the identifier of another entity, resulting in a composite key that often includes a foreign key from the parent entity.

Multiple Relationships (Same Entities)

When converting an ER model with multiple relationships between the same two entities, each relationship results in a separate foreign key in the relational model, typically with different names to distinguish them.

Unary Relationship

A relationship of Degree 1 where an entity is related to itself; in conversion, the entity's key is added as a foreign key in the same relation, typically renamed to avoid confusion.