16 Questions
What is the correct terminology for the components of a relation?
Relation, tuple, attribute
What is a key characteristic of a relation in a database?
Tuples are distinct; there are no duplicates
What is a super key in the context of database systems?
A set of attributes that uniquely identifies a tuple within a relation
What is true about a candidate key in a database system?
It is a super key with no proper subset being a super key
What is a composite key in a database system?
A key consisting of more than one attribute
What does a foreign key represent in a database system?
An attribute that matches the primary key of another relation
What does the entity integrity constraint state in a database system?
No attribute of a primary key can be null
What is a base relation in a database system?
A named relation stored in the database
What represents a physically stored relation in the database?
Relation
What is represented by an entity type in the ER model?
A relationship between objects
What is a relationship type in the ER model?
A set of meaningful associations among entity types
What is an attribute in the ER model?
A property of an entity or a relationship type
What is the difference between a composite attribute and a simple attribute?
Composite attributes can be divided into smaller subparts; simple attributes cannot
What is a multivalued attribute?
An attribute that can have multiple values for each entity
What is a derived attribute?
An attribute that is calculated from other attributes
What does a value set or domain represent for an attribute?
The set of all possible values for an attribute
Study Notes
Database Systems: Components and Terminology
- A relation consists of tuples (rows) and attributes (columns)
- Correct terminology: relation, tuple, attribute
- Attributes can have distinct names, but no duplicates
Properties of Relations
- Each cell contains exactly one atomic value
- Tuples are distinct, no duplicates
- The order of attributes has no significance
Keys
- A super key is a set of attributes that uniquely identifies a tuple within a relation
- A candidate key is a super key with no proper subset being a super key
- A primary key is a selected candidate key for each relation
- A composite key consists of more than one attribute
Foreign Keys
- A foreign key represents an attribute that matches the primary key of another relation
- Foreign keys must match a candidate key value or be null
Entity Integrity Constraint
- No attribute of a primary key can be null
Base Relations and Views
- A base relation is a named relation stored in the database
- A view is a dynamic result of relational operations on base relations
ER Model: Entity Types, Relationships, and Attributes
- An entity type represents a group of objects with the same properties
- A relationship type represents a set of meaningful associations among entity types
- An attribute is a property of an entity or a relationship type
Attributes in ER Model
- A composite attribute can be divided into smaller subparts
- A multivalued attribute can have multiple values for each entity
- A derived attribute is calculated from other attributes
- A value set or domain represents the set of all possible values for an attribute
Assess your knowledge of database systems with these 40 multiple-choice questions covering topics such as relations, attributes, and tuples. Test your understanding of database fundamentals and concepts.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
