Module1: Conceptual Data Modelling Flashcards
What is conceptual modelling in database design?
Conceptual modelling is the process of abstracting a model from the real world to represent the data structure, relationships, and constraints in a database application.
What is the Entity-Relationship Model? (ER model)
The ER model is a graphical approach to database design that outlines the entities involved in a system and their relationships, making it easier to conceptualize the database structure.
What are entities in the ER Model?
Entities are objects or concepts that can have data stored about them in a database. They are represented as rectangles in ER diagrams.
What represents relationships in the ER Model?
Relationships are associations between entities, represented by diamonds in ER diagrams, indicating how entities are connected.
What are attributes in the context of the ER Model?
Attributes are properties or details that describe entities, represented by ovals connected to their entity rectangle in ER diagrams.
What is cardinality in the ER Model?
Cardinality defines the numerical relationship between entities, such as one-to-one, one-to-many, or many-to-many.
What are participation constraints in the ER Model?
Participation constraints specify the minimum and maximum number of times an entity can participate in a relationship.
What is a weak entity in the ER Model?
A weak entity cannot be uniquely identified by its own attributes alone and relies on a foreign key from another entity, represented by double rectangles.
What is the purpose of ER diagrams?
ER diagrams visually represent the entities, relationships, and attributes of a database, aiding in its conceptual design.
What are some design choices to consider in ER modelling?
Design choices include deciding between using attributes or entities for certain data, the level of normalization, and how to represent hierarchical relationships.
What is the primary purpose of an Entity-Relationship (ER) Diagram?
A) To define the syntax of a programming language
B) To visually represent the database schema
C) To outline the physical storage of data
D) To program database transactions
B) To visually represent the database schema
In the ER Model, what does a diamond symbolize?
A) Entity
B) Attribute
C) Relationship
D) Cardinality
C) Relationship
Which of the following best defines ‘Cardinality’ in the context of ER diagrams?
A) The attributes of an entity
B) The maximum number of entities involved in a relationship
C) The specific roles of entities in a relationship
D) The unique identifier for each entity
B) The maximum number of entities involved in a relationship
