Lesson 4

Question 1

entity-relationship (ER) model

Answer 1

high-level representation of data requirements, ignoring implementation details

Question 2

Entity

Answer 2

person, place, product, concept, or activity

Question 3

Relationship

Answer 3

statement about two entities

Question 4

Attribute

Answer 4

descriptive property of an entity

Question 5

Reflexive relationship

Answer 5

relates an entity to itself

Question 6

ER diagram

Answer 6

schematic picture of entities, relationships, and attributes

Question 7

Entity type

Answer 7

set of things

Question 8

Relationship type

Answer 8

set of related things

Question 9

Attribute type

Answer 9

set of values

Question 10

Entity instance

Answer 10

Individual thing

Question 11

Relationship instance

Answer 11

statement about entity instances

Question 12

attribute instance

Answer 12

Individual value

Question 13

Analysis for Database Design

Answer 13

Conceptual design

Question 14

Strong entity

Answer 14

entity with own primary key

can exist independent of other entities

Question 15

Weak entity

Answer 15

entity with composite key

must depend on strong entities to exist

Question 16

cardinality

Answer 16

refers to maxima and minima of relationships and attributes

*one-to-one
*one-to-many
*many-to-many

Question 17

Relationship maximum

Answer 17

Greatest number of instances of one entity that can relate to a single instance of another entity

one-to-many

Question 18

Relationship minimum

Answer 18

Least number of instances of one entity that can relate to a single instance of another entity

Question 19

Subtype entity

Answer 19

subset of another entity type, called the supertype entity

Question 20

partition

Answer 20

A partition of a supertype entity is a group of mutually exclusive subtype entities

Question 21

Database Design

Answer 21

After entities, relationships, attributes, cardinality, and strong and weak entities are determined, the designer looks for supertype and subtype entities.

Question 22

crow’s foot notation

Answer 22

depicts cardinality as a circle (zero), short line (one), or three short lines (many)

Question 23

Artificial Key

Answer 23

single column primary key created by the database designer when no suitable single column or composite primary key exist

Question 24

functional dependence

Answer 24

dependence of one column on another

Question 25

Redundancy

Answer 25

repetition of related values in a table

Question 26

Normal forms

Answer 26

rules for designing tables with less redundancy

Learn Database Normalization - 1NF, 2NF, 3NF, 4NF, 5NF

Question 27

candidate key

Answer 27

simple or composite column that is unique and minimal

a table can have multiple candidate key

Question 28

non-key

Answer 28

column that is not a possible candidate key

Question 29

Normalization

Answer 29

Eliminates redundancy by decomposing a table into two or more tables

Redundancy is eliminated with normalization

Last step of the Logical design

Question 30

trivial dependencies

Answer 30

When the columns of A are a subset of the columns of B, with A always depending on B

Question 31

Denormalization

Answer 31

intentionally introducing redundancy by merging tables to eliminate JOIN queries

Question 32

Boyce-Codd normal form

Answer 32

ideal for tables with frequent inserts, updates, and deletes

Question 33

IsA

Answer 33

supertype entity identifies its subtype entities

Question 34

Attribute minimum

Answer 34

Least number of attribute values that can describe each instance

Appears in parentheses