Introductory Info
What is data modelling?
Data modelling serves as a bridge between real-world object and the computer database.
What is evolution?
A gradual process of change and development
The way in which living things change and develop over millions of years
What is a tuple?
A row in a table
What is inheritance?
New objects can inherit attributes and methods from existing objects
What is a person who creates models and layouts for databases called?
A database designer
What is a data model?
A data model is a simple representation of more complex real-world data structures
What is the first gen of data models?
File Systems
What is referential integrity?
When one attribute of a relation can only take values from another attribute of the same relation or any other relation
What is encapsulation?
Protects the internal details of objects by only exposing what’s necessary.
What is a primary key?
A unique identifier for each row in a table. It ensures that each record can be uniquely identified.
What are two objectives of data modelling?
To represent reality
To facilitate communication
To act as a design blueprint
What are the 2 second gen data models?
Hierarchial and network models
What are the three ER model notations?
Chen Notation
Crow's Foot Notation
UML Class Diagram Notation
Why do we use UML representation?
The Unified Modeling Language (UML) helps visualize databases with diagrams.
What are the two requirements for primary keys?
Must be unique
Must not be null
What are the 4 building blocks of data models?
Entities
Attributes
Relationships
Constraints
What are shemas and subschemas?
Schema
The Conceptual organization of the entire database as viewed by the database administrator
Subschema
Database portion “seen” by the application programs
What does a rectangle represent in the ER model?
Entities
What are 2 features of NoSQL?
Schema Flexibility
Scalability
High Performance
What concept refers to the intentional duplication of data in a database to improve its performance.
Controlled redundancy
What are 3 reasons business rules are essential in data modelling?
Translate organizational policies into formal data structures
Clarify processes, reduce ambiguity, and enforce consistency
Help to standardize the company view of data
Can be a communication tool between users and designers
Allow the designer to understand the nature, role, and scope of the data.
They allow the designer to understand business processes.
Allow the designer to develop appropriate rules and constraints
What is time-series data modelling?
Time-series databases (TSDB) are designed specifically for housing data records associated with timestamps. That is, they are ideal for use cases where an event’s occurrence(s) are the primary dimension of concern. This allows users to see how data evolves over time.
What are 4 supported operations of the ER model
Projection
Join
Union
Intersection
What are the three levels of data abstraction?
External Level (User View)
This is how users interact with the database. Each user sees data tailored to their needs.
Conceptual Level (Logical View)
Defines the overall structure of the database, including entities, relationships, and constraints.
Internal Level (Physical Storage)
Deals with how data is physically stored, such as file structures and indexing.
What is data about data called?
Metadata