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Questions and Answers
What is represented by a diamond-shaped box in an ER diagram?
What is represented by a diamond-shaped box in an ER diagram?
What is the degree of the relationship types identified in the COMPANY database schema?
What is the degree of the relationship types identified in the COMPANY database schema?
What is the relationship type that represents the connection between an EMPLOYEE and a PROJECT?
What is the relationship type that represents the connection between an EMPLOYEE and a PROJECT?
What is the purpose of a relationship set?
What is the purpose of a relationship set?
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What is the term for the relationship type that identifies the relationship name and the participating entity types?
What is the term for the relationship type that identifies the relationship name and the participating entity types?
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Which of the following is an example of a participating entity type in the WORKS_FOR relationship?
Which of the following is an example of a participating entity type in the WORKS_FOR relationship?
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What is the relationship type that represents the connection between a DEPARTMENT and a PROJECT?
What is the relationship type that represents the connection between a DEPARTMENT and a PROJECT?
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What is the term for the current set of relationship instances in the database?
What is the term for the current set of relationship instances in the database?
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Which of the following is NOT a relationship type identified in the COMPANY database schema?
Which of the following is NOT a relationship type identified in the COMPANY database schema?
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What is the purpose of a relationship type?
What is the purpose of a relationship type?
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Study Notes
Database Design Process
- The database design process consists of two main activities: database design and applications design
- Database design focuses on designing the conceptual schema for a database application
- Applications design focuses on the programs and interfaces that access the database, which is part of software engineering
Entity-Relationship (ER) Model
- The ER model is a conceptual representation of data
- It has three main concepts: entities, attributes, and relationships
- Entities are objects with existence and can be described with attributes
- Attributes can be simple, composite, or multivalued
Entities and Attributes
- Entities can be categorized into entity types and entity sets
- Entity types are categories of entities, and entity sets are collections of entities
Relationships and Relationship Types
- A relationship is an association between two or more entities with a specific meaning
- Relationships can be grouped into relationship types
- Relationship types have a degree, which is the number of participating entity types
- Examples of relationships include WORKS_ON and MANAGES
Relationship Instances and Relationship Sets
- A relationship instance is a specific instance of a relationship type
- A relationship set is the current set of relationship instances in the database
- A relationship set represents the current state of a relationship type
ER Diagrams
- ER diagrams are used to represent the ER model
- Relationship types are represented by diamond-shaped boxes
- Participating entity types are connected to the relationship type via lines
COMPANY Database Schema
- The COMPANY database schema includes entities such as DEPARTMENT, PROJECT, and EMPLOYEE
- Relationships between entities include WORKS_FOR, MANAGES, WORKS_ON, CONTROLS, SUPERVISION, and DEPENDENTS_OF
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Description
This quiz covers the basics of data modeling using the Entity-Relationship (ER) Model, including entities, attributes, relationships, and more.
