Chapter 2 Flashcards
What are data models?
Data models are simple graphical representations of complex real-world structures.
What is the importance of data models?
facilitate interaction among the designer, the applications programmer and end-user.
Organizes data for various users.
What is an entity?
Anything about data that is about to be stored and collected.
What is an attribute?
A characteristic of an entity.
What is a relationship?
An association among entities.
What are the types of relationships?
One-to-many (1:) relationship
Many-to-many (:*) relationship
One-to-one (1:1) relationship
What is a constraint?
It is a restriction placed on data.
List the sources of business rules.
Company managers
Policy-makers
Department managers
Written Documentation
Direct Interviews with end-users
What are business rules?
Brief and precise policies within a specific organization that stores and uses data to generate information.
What are the types of data models?
Hierarchical
Network
Relational
Entity relationship
Object oriented (OO)
Briefly describe the relational model in detail.
Developed by Codd(IBM) in 1970
Ingenious but impractical in 1970
Conceptually simple
Computers back then lacked power to implement relational model
Microcomputers today can run relational database software.
Know the evolution of data models.
AYT BET.
How many generations of data models are there?
6 with the emerging models like NoSQL.
Give some examples of Hierarchical and Network Databases.
IMS, ADABAS, IDS-II
Give some characteristics of the Hierarchical and Network Databases.
They used:
Early database systems
Navigational Access
Give some examples of a Relational Database.
DB2
Oracle
MySQL
MySQL Server
Give some characteristics of the Relational Database.
It is Conceptually simple
It Supports ER Modelling
Give some examples of an Object-oriented Database.
Versant.
DB2 UDB
DB
Oracle 11g
Give some characteristics of the Object-oriented Database.
Supports object data types.
Web databases become common.
Supports Star Schema for data warehousing.
What is the advantage of the RDBMS?
It can hide the complexities of the relational model from the user.
What is a relational diagram?
It is a representation of relational database’s entities, attributes within those entities, and the relationships between those entities.
What role does SQL play in relational databases?
Allows user to specify what must be done without specifying how it must be done.
What does an SQL-based relational database consist of?
A User Interface
Set of tables in the database
SQL Engine
What is an Entity Relationship (ER) Model defined as?
It is a graphical representation of entities and their relationships in a database structure.
Introduced by Chen in 1976
What is Big Data?
It is managing large web data for business insights, performance, and scalability at a good cost.
