Database Systems Quiz

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson
Download our mobile app to listen on the go
Get App

Questions and Answers

What is the correct terminology for the components of a relation?

  • Entity, instance, value
  • Table, row, column
  • Relation, tuple, attribute (correct)
  • Set, element, property

What is a key characteristic of a relation in a database?

  • Tuples are distinct; there are no duplicates (correct)
  • The order of attributes has significance
  • Tuples can have duplicate values
  • Attributes can have duplicate names

What is a super key in the context of database systems?

  • A set of attributes that uniquely identifies a tuple within a relation (correct)
  • The primary key of a relation
  • An attribute that uniquely identifies a relation
  • A foreign key referencing another relation

What is true about a candidate key in a database system?

<p>It is a super key with no proper subset being a super key (D)</p> Signup and view all the answers

What is a composite key in a database system?

<p>A key consisting of more than one attribute (D)</p> Signup and view all the answers

What does a foreign key represent in a database system?

<p>An attribute that matches the primary key of another relation (D)</p> Signup and view all the answers

What does the entity integrity constraint state in a database system?

<p>No attribute of a primary key can be null (A)</p> Signup and view all the answers

What is a base relation in a database system?

<p>A named relation stored in the database (B)</p> Signup and view all the answers

What represents a physically stored relation in the database?

<p>Relation (B)</p> Signup and view all the answers

What is represented by an entity type in the ER model?

<p>A relationship between objects (B)</p> Signup and view all the answers

What is a relationship type in the ER model?

<p>A set of meaningful associations among entity types (B)</p> Signup and view all the answers

What is an attribute in the ER model?

<p>A property of an entity or a relationship type (A)</p> Signup and view all the answers

What is the difference between a composite attribute and a simple attribute?

<p>Composite attributes can be divided into smaller subparts; simple attributes cannot (B)</p> Signup and view all the answers

What is a multivalued attribute?

<p>An attribute that can have multiple values for each entity (C)</p> Signup and view all the answers

What is a derived attribute?

<p>An attribute that is calculated from other attributes (D)</p> Signup and view all the answers

What does a value set or domain represent for an attribute?

<p>The set of all possible values for an attribute (C)</p> Signup and view all the answers

Flashcards

Relation components

Relation, tuple, and attribute.

Key relation characteristic

All tuples (rows) are distinct; no duplicates are allowed.

Super key

A set of attributes that uniquely identifies each tuple (row) in a relation (table).

Candidate key

A super key where no subset of its attributes is also a super key (minimal super key).

Signup and view all the flashcards

Composite key

A key that consists of two or more attributes combined to uniquely identify a tuple.

Signup and view all the flashcards

Foreign key

An attribute in one relation that refers to the primary key of another relation.

Signup and view all the flashcards

Entity integrity constraint

No attribute of a primary key can contain a null value.

Signup and view all the flashcards

Base Relation

A relation that is physically stored in the database.

Signup and view all the flashcards

Relation (physical)

A named relation stored in the database.

Signup and view all the flashcards

Entity Type

A collection of entities that share common properties.

Signup and view all the flashcards

Relationship type

A set of meaningful associations among two or more entity types.

Signup and view all the flashcards

Attribute (ER Model)

A property or characteristic of an entity or relationship.

Signup and view all the flashcards

Composite vs. Simple Attribute

Composite attributes can be divided; simple attributes cannot.

Signup and view all the flashcards

Multivalued attribute

An attribute that can hold multiple values for a single entity.

Signup and view all the flashcards

Derived attribute

An attribute calculated from other attributes; it's not directly stored.

Signup and view all the flashcards

Value set / Domain

The set of all possible values an attribute can hold.

Signup and view all the flashcards

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

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser