Chapter 3 - The Relational Database Model

Question 1

Attribute domain

Answer 1

Specific range of values for an attribute.

Question 2

Candidate Key

Answer 2

A minimal (irreducible) superkey; a superkey that does not contain a subset of attributes that is itself a superkey.

Question 3

Closure

Answer 3

Use of relational algebra operators on existing relations produces new relations.

Question 4

Composite Entity

Answer 4

AKA Bridge or Associative entity. Helps avoid problems inherent to M:N relationships, includes the primary keys of tables to be linked

Question 5

Composite key

Answer 5

Key that is composed of more than one attribute

Question 6

Data Dictionary

Answer 6

Description of all tables in the database created by the user and designer. Metadata, data about the data.

Question 7

Dependent

Answer 7

Attribute whose value is determined by the other attribute.

Question 8

Determinant

Answer 8

Attribute whose value determines another.

Question 9

Determination

Answer 9

State in which knowing the value of one attribute makes it possible to determine the value of another.

Question 10

Domain

Answer 10

In data modeling, the construct used to organize and describe an attribute’s set of possible values.

Question 11

Entity Integrity

Answer 11

Condition in which each row in the table has its own unique identity. All values in PK must be unique and no key attribute in the primary key can contain a null.

Question 12

Equijoin

Answer 12

Links tables on the basis of an equality condition that compares specified columns of each table.

Question 13

Flags

Answer 13

Special codes used to indicate the absence of some value.

Question 14

Foreign Key (FK)

Answer 14

An attribute or combination of attributes in one table whose values must either match the primary key in another table or be null.

Question 15

Full Functional Dependence

Answer 15

Entire collection of attributes in the determinant is necessary for the relationship.

Question 16

Functional Dependence

Answer 16

Value of one or more attributes determines the value of one or more other attributes.

Question 17

Homonym

Answer 17

Same name is used to label different attributes.

Question 18

Index

Answer 18

Orderly arrangement to logically access rows in a table. Associated to only one table.

Question 19

Index Key

Answer 19

Index’s reference point that leads to data location identified by the key.

Question 20

Inner Join

Answer 20

Only returns matched records from the tables that are being joined.

Question 21

Join Column(s)

Answer 21

Common columns in a natural join.

Question 22

Key

Answer 22

An entity identifier based on the concept of functional dependence.

Question 23

Key Attribute

Answer 23

Attribute that is a part of a key

Question 24

Left Outer Join

Answer 24

Yields all of the rows in the first table, including those that do not have a matching value in the second table.

Question 25

Linking Table

Answer 25

In the relational model, a table that implements an M:M relationship.

Question 26

Natural Join

Answer 26

Links tables by selecting only the rows with common values in their common attributes.

Question 27

Null

Answer 27

Absence of any data value that could represent:

Question 28

Outer Join

Answer 28

Matched pairs are retained and unmatched values in the other table are left null.

Question 29

Predicate Logic

Answer 29

Used extensively in mathematics to provide a framework in which an assertion (statement of fact) can be verified as either true or false.

Question 30

Primary key (PK)

Answer 30

Attribute or combination of attributes that uniquely identifies any given row.

Question 31

Referential Integrity

Answer 31

Every reference to an entity instance by another entity instance is valid.

Question 32

Relational Algebra

Answer 32

Theoretical way of manipulating table contents using relational operators.

Question 33

Relvar

Answer 33

Variable that holds a relation

Question 34

Right Outer Join

Answer 34

Yields all of the rows in the second table, including those that do not have matching values in the first table.

Question 35

Secondary Key

Answer 35

An attribute or combination of attributes used strictly for data retrieval purposes.

Question 36

Set Theory

Answer 36

A part of mathematical science that deals with sets, or groups of things, and is used as the basis for data manipulation in the relational model.

Question 37

Superkey

Answer 37

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

Question 38

Synonym

Answer 38

Different names are used to describe the same attribute.

Question 39

System Catalog

Answer 39

System data dictionary that describes all objects within the database.

Question 40

Theta Join

Answer 40

Extension of natural join, denoted by adding a theta subscript after the JOIN symbol.

Question 41

Tuple

Answer 41

A table row that represents a single entity occurrence within the entity set.

Question 42

Union-Compatible

Answer 42

Tables share the same number of columns, and their corresponding columns share compatible domains.

Question 43

Unique Index

Answer 43

Index key can have only one pointer value associated with it.