Module 3: The Relational Database Model Flashcards

Vocabulary flashcards covering key terms, relational algebra operations, integrity rules, and database structural concepts from Chapter 3 of Database Systems (14th Edition).

Relation

A two-dimensional logical structure composed of rows and columns, also known as a table, whose contents can be permanently saved for future use.

Tuple

A single row in a relational table representing a single entity occurrence within an entity set.

Attribute Domain

The specific range of allowable values for a given column or attribute in a table.

Primary Key (PK)

An attribute or combination of attributes that uniquely identifies any given row in a table.

Functional Dependence

A relationship where the value of one or more attributes uniquely determines the value of one or more other attributes.

Determinant

The attribute or group of attributes whose value determines the value of another attribute in a functional dependence relationship.

Dependent

The attribute whose value is determined by another attribute or group of attributes in a functional dependence relationship.

Full Functional Dependence

A functional dependence in which the entire collection of attributes in the determinant is necessary to determine the dependent attribute.

Composite Key

A key that is composed of more than one attribute.

Superkey

Any key consisting of an attribute or set of attributes that can uniquely identify any row in a table.

Candidate Key

A minimal superkey that contains no subset of attributes that is itself a superkey.

Entity Integrity

The integrity rule requiring that all primary key entries be unique and no part of a primary key be null, ensuring each row has a known, unique identity.

Null

The absence of a data value in a field, which can represent an unknown attribute value, a missing value, or a not-applicable condition.

Foreign Key (FK)

A primary key of one table that has been placed into another table to establish a logical link between them.

Referential Integrity

The condition requiring that a non-null foreign key entry must match an existing primary key value in the related table.

Secondary Key

A key used strictly for data retrieval purposes that does not require a functional dependency.

Relvar

Short for relation variable; a structure holding relation data that consists of a heading (attribute names) and a body (the relation).

SELECT (RESTRICT)

A relational algebra operator used to select a subset of rows from a table based on specified criteria.

PROJECT

A relational algebra operator used to select a subset of columns from a table.

UNION

A relational algebra operator that combines all rows from two union-compatible tables into a single table, dropping duplicate rows.

INTERSECT

A relational algebra operator that yields only the rows common to two union-compatible tables.

DIFFERENCE

A relational algebra operator that yields all rows in one table that are not found in another union-compatible table.

PRODUCT

A relational algebra operator that yields all possible pairs of rows from two tables, also known as the Cartesian product.

Natural JOIN

A relational algebra operator that links tables by selecting only rows with common values in their shared attributes.

Equijoin

A JOIN operation that links tables on the basis of an equality condition comparing specified columns of each table.

Theta Join

A JOIN operation that links tables using an inequality comparison operator.

Inner Join

A JOIN operation that returns only matched records from the tables being joined.

Outer Join

A JOIN operation in which matched pairs are retained and unmatched values from either table are left null.

DIVIDE

A relational algebra operator used to answer questions about one set of data being associated with all values of data in another set of data.

Data Dictionary

A detailed description of all tables in the database created by the user and designer, recording design decisions about table structures.

System Catalog

A detailed system data dictionary that describes all objects within the database.

Homonym

A database design error where the same name is used to label different attributes.

Synonym

A database design error where different names are used to describe the same attribute.

Composite Entity

A table created to resolve a many-to-many (M:N) relationship into two one-to-many (1:M) relationships, containing foreign keys referencing the linked tables.

Index

An orderly arrangement used to logically access rows in a table.

Index Key

The reference point in an index that leads directly to the data location identified by the key.

Components of an Index

An index structure composed of index keys (such as PAINTER_NUM) and pointers referencing specific rows in a target table.