CS401A's Midterms: Info Management Module 03

Question 1

Fundamentals

introduced by E. F. Codd in 1970,

Answer 1

• The relational model,

Question 2

Fundamentals

is based on predicate logic and set theory.

Answer 2

• The relational model,

Question 3

relational model

is used extensively in mathematics to provide a framework in which an assertion can be verified as either true or false.

(statement of fact)

Answer 3

○ Predicate logic

Example: A student with a student ID of 324452 is named Mark Reyes.

Question 4

relational model

is 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.

Answer 4

○ Set theory

Example: Set A contains 15, 23, and 52 while Set B contains 41, 52, 70, 12. It can be concluded that the A and B share a common value, 52.

Question 5

relational model

• The relational model has three (3) components:

Answer 5

1. A logical data structure represented by relations
2. A set of integrity rules to enforce that the data is consistent and remains consistent over time
3. A set of operations that defines how data is manipulated

Question 6

relational model

is as a two-dimensional structure composed of rows and columns.

Answer 6

• A table (relation)

Question 7

relational model

represents data about an entity.

Answer 7

• Each table row (tuple)

Question 8

relational model

• Each table column represents

Answer 8

an attribute,

and each column has a distinct name.

Question 9

relational model

• Each represents a single data value.

Answer 9

intersection of a row and column

Question 10

relational model

Each column has a specific range of values known as

Answer 10

the attribute domain.

Question 11

TRUE || FALSE

The order of the rows and columns is important in a DBMS.

Answer 11

FALSE

Question 12

is an attribute or group of attributes that determines the values of other attributes.

Answer 12

A key

For example, an invoice number identifies all of the invoice attributes, such as the invoice date and the customer name.

Question 13

Keys

is the state in which knowing the value of an attribute makes it possible to determine the value of another.

Answer 13

Determination

Question 14

Keys

It is based on the relationships among the attributes.

Answer 14

• Determination

Question 15

Keys

means that the value of one or more attributes determines the value of one or more other attributes.

Answer 15

Functional dependence

Question 16

Keys

The attribute whose value determines another is called

Answer 16

the determinant or the key.

Question 17

Keys

The attribute whose value is determined by the other attribute is called the

Answer 17

dependent.

Question 18

• Data can be manipulated to generate useful information.

Answer 18

Relational Algebra

Question 19

is a set of mathematical principles that form the basis for manipulating relational table contents.

Answer 19

• Relational algebra

Question 20

• The use of relational algebra operators on existing relations (tables) produces new relations is called

Answer 20

closure.

Question 21

• The condition to be evaluated is also known as

Answer 21

predicate.

Question 22

• The eight (8) fundamental relational operators are:

Answer 22

SELECT
PROJECT
UNION
INTERSECT
DIFFERENCE
PRODUCT
JOIN
DIVIDE

Question 23

Retrieves a subset of rows

Answer 23

SELECT

Question 24

Symbol

σ

Answer 24

SELECT

Operator

Question 25

Retrieves a subset of columns

Answer 25

PROJECT

Question 26

Symbol

π

Answer 26

PROJECT

Question 27

Merges two union-compatible tables into a new table, dropping the duplicate rows

Answer 27

UNION

Question 28

Symbol

∪

Answer 28

UNION

Question 29

Retrieves rows that are common to two union-compatible tables

Answer 29

INTERSECT

Question 30

Symbol

∩

Answer 30

INTERSECT

Question 31

Retrieves rows from one table that are not found in another union-compatible table

Answer 31

DIFFERENCE

Question 32

Symbol

-

Answer 32

DIFFERENCE

Question 33

Retrieves possible pairs of rows from two tables

Answer 33

PRODUCT

(Cartesian Product)

Question 34

Symbol

x

Answer 34

PRODUCT

Question 35

Retrieves rows from two tables based on criteria

(Ex. Rows with common values in their common attributes)

Answer 35

JOIN

Question 36

Symbol

⋈

Answer 36

JOIN

Question 37

Retrieves values

Answer 37

DIVIDE

Question 38

Symbol

÷

Answer 38

DIVIDE