Data Models Flashcards
What is data modeling?
The process of creating a specific data model for a determined problem domain.
Data modeling is the first step in designing a database.
What are the three phases of database design?
- Information Requirements Phase
- Logical Design Phase
- Physical Design Phase
Information Requirements Phase - identify information requirements
Logical Design Phase - build data model
Physical Design Phase - implement data model
Define ‘entity’ in data modeling.
Anything about which data are to be collected and stored.
Entities are “distinguishable” — that is, each entity occurrence is unique and distinct
What is an attribute?
A characteristic of an entity.
What does a relationship describe in data modeling?
An association among entities.
What type of relationship is represented by ‘PAINTER paints PAINTING’?
One-to-many (1:M) relationship.
What is a business rule?
A brief, precise, and unambiguous description of a policy, procedure, or principle within a specific organization.
How do nouns and verbs translate in data modeling?
Nouns translate into entities and verbs translate into relationships.
How is information represented in a hierarchical model?
An upside-down tree structure with parent/child relationships.
What is the significance of the network model?
It represents complex data relationships more effectively than the hierarchical model.
Who developed the relational model and when?
Edgar Frank Codd (IBM) developed it in 1970.
What is a tuple in the context of a relational database?
Each row in a relation.
What does an Entity Relationship Diagram (ERD) represent?
Graphical representation of entities and their relationships in a database structure.
Define ‘object’ in the Object-Oriented Model.
Data and relationships contained in a single structure.
An object
- contains operations
- self-contained: basic building-block for autonomous structures
- abstraction of real-world entity
What is inheritance in the context of Object-Oriented Database Model?
An object inherits methods and attributes of its parent class.
Multidimensional data model is designed to do what?
Designed to solve complex queries in real time
What is NoSQL designed to address?
Large structured and unstructured data across various locations.
What does the external model represent?
End users’ view of the data environment.
What is the purpose of the conceptual model?
Represents a global view of the entire database.
What does the internal model represent?
Representation of the database “as seen” by the DBMS
Maps the conceptual model to the DBMS
What does the physical model describe?
The way data are saved on storage media.
True or False: The relational model requires physical-level details.
False
What are the three types of relationships among data?
- One-to-many (1:M)
- Many-to-many (M:N)
- One-to-one (1:1)
What does logical independence refer to?
Change in internal model without affecting conceptual model.
