Block 2, Part 4: Conceptual Models Flashcards
What is a conceptual data model?
A high-level description of the database that is detailed enough to be used by technical stakeholders but still easily understood by non-technical stakeholders.
What does a conceptual data model capture?
Definitions of entities, their attributes, relationships and constraints.
What is a data dictionary?
The agreed definitions/descriptions of the terms used in the domain of discourse for a database.
What is the entity-relationship model?
A visual representation for a database design.
What does the entity-relationship model diagram capture?
The entity types of interest, the attributes of the entity types and their domain, the relationship types and their description, and constraints that limit the values and relationships within the model.
What does an entity type represent?
A set of artefacts that have the same data requirements; that are recognised by the organisation; and whose data representation captures something of importance to the organisation.
What is an entity instance?
A single occurrence of an entity type.
What are entity attributes?
An attribute is a property of an entity type, such as a name, an identifier, etc.
What is an attribute domain?
A domain is a named set of values from which attributes can draw their own values.
What is a key attribute of an entity type?
A unique identifier of an individual instance of the entity type.
What is a candidate key?
One possible key for an entity type.
What is a relationship type?
A description of the asocial between entity types that are of importance in the domain of discourse.
What is a relationship instance?
A specific occurrence of a relationship type that holds between entity instances.
What does optionality mean in reference to a relationship type?
Optionality defines whether or not it is a requirement of every instance of the entity type to take part in an instance of the relationship type.
What does degree/multiplicity mean in reference to a relationship type?
Degree/multiplicity describes if an entity instance can be involved in at most one relationship instance, or can be involved in one or more relationship instances.
