database model

Question 1

Collection of logical constructs used to represent the data
structure and the data relationships found within the database.

Answer 1

DATABASE MODELS

Question 2

Focuses on the logical nature of the data representation

Answer 2

Conceptual model

Question 3

Has an emphasis on how data are represented in the database or on
how data structures are implemented to represent what is modeled.

Answer 3

Implementation model

Question 4

Collection of records logically organized to conform to the
upside-down tree (hierarchical) structure. The structure allows representing information using parent/child
relationships: each parent can have many children, but each child
has only one parent (also known as a 1-to-many relationship).

Answer 4

Hierarchical Database Model

Question 5

On the model, the employee data table represents the “parent”
part of the hierarchy, while the computer table represents the
“child” part of the hierarchy.

Answer 5

True

Question 6

is a database model conceived as a flexible way of representing
objects and their relationships.

Answer 6

Network Database Model

Question 7

perceived as a collection of tables, tables are related to each other by sharing a common entity characteristic (foreign key),
It uses a structure that allows us to identify and access data in
relation to another piece of data in the database.

Answer 7

Relational Database Model

Question 8

a person, place, event, or thing for which we intend to collect
data

Answer 8

Entity

Question 9

characteristics of each entity
Student – student number, name, address, contact number

Answer 9

Attributes

Question 10

collection of entities that share common characteristics

Answer 10

Entity set

Question 11

two-dimensional structure composed of rows and columns

Answer 11

Table

Question 12

Characteristics of a Relational Table:
*Each table row (tuple) represents a single entity within the entity set
*Each column represents an attribute, and each column has a distinct name
*Each row/column intersection represents a single data value

Answer 12

True

Question 13

An object is described by its factual content.

Answer 13

Object-Oriented Database Model

Question 14

are abstractions of real-world entities or events.

Answer 14

Objects

Question 15

is a collection of similar objects with shared structure
(attributes) and behavior (methods); organized in class a hierarchy

Answer 15

class

Question 16

An object can inherit the attributes and methods of the classes

Answer 16

True

Question 17

graphically represents data as entities and their relationships in a database structure

Answer 17

Entity Relationship Model

Question 18

Diagrams created by this process are called

Answer 18

entity-relationship diagrams, ER diagrams, or ERDs.

Question 19

A relationship expressed with a verb that implies direction,
makes it impossible to discuss the model using correct English.

Answer 19

Relationship Names

Question 20

It has also become prevalent to name roles with phrases e.g.
is-the-owner-of and is-owned-by etc.

Answer 20

Role naming

Question 21

Set or group of set used in database

Answer 21

Cardinalities

Question 22

Set or group of set used in database

This includes:

Answer 22

One to one

One to many

Many to one

Many to many

Question 23

A single row of first table associates with single row of second table.

Answer 23

One to One

Question 24

A single row of first table associates with more than one rows of second table.

Answer 24

One to Many

Question 25

Many rows of first table associate with a single row of second table.

Answer 25

Many to One

Question 26

Many rows of first table associate with many rows of second table.

Answer 26

Many to Many

Question 27

represent entities as boxes, and relationships as lines between the boxes.

Answer 27

Crow's Foot diagrams

Question 28

Different shapes at the ends of these lines represent the cardinality of the relationship.

Answer 28

Crow's Foot Notation

Question 29

Relationships have two indicators, shown on both sides of the line.

Answer 29

True

Question 30

In crow’s foot notation: A multiplicity of one and a mandatory relationship is represented by a straight line perpendicular to the relationship line. A multiplicity of many is represented by the three-pronged ‘crow-foot’ symbol. An optional relationship is represented by an empty circle.

Answer 30

True

Question 31

Enables programmer to view data logically rather than physically

Answer 31

Relational model

Question 32

has advantages of structural and data independence

Answer 32

Table

Question 33

consists of one or more attributes that determine other attributes

Answer 33

Keys

Question 34

key that is composed of more than one attributes that uniquely identifies a record on a table

Answer 34

Composite key

Question 35

an attribute that uniquely identifies each entity in a table

Answer 35

Superkey

Question 36

Super Key is a superset of Candidate key.

Answer 36

True

Question 37

student_id is unique for every row of data, hence it can be used to identity each row uniquely.

Answer 37

True

Question 38

Superkey can have redundancies

Answer 38

True

Question 39

defined as the minimal set of fields which can uniquely identify each record in a table.

Answer 39

Candidate key

Question 40

A candidate key can never be NULL and its value should be unique.

Answer 40

True

Question 41

There can be more than one candidate keys for a table.

Answer 41

True

Question 42

candidate key that uniquely identifies all other attribute values in any given row.

Answer 42

Primary key

Question 43

attribute whose values match the primary key values in the related table.

Answer 43

Foreign key

Question 44

key that is used for data retrieval purposes.

Answer 44

Secondary key