Lesson 2 - Week 3-4

Question 1

Database Designing Process

Answer 1

• Requirement collection
• Conceptual schema
• Basic data model operations
• Actual implementation of database
• Physical database design

Question 2

____ models help the designer in describing data at the logical level. This type of model provides flexible capabilities which let constraints be clearly defined.

Answer 2

Object-based logical models

Question 3

____ models are used to state the general logical structure of the database and to offer an advanced description of the implementation.

Answer 3

Record-based logical models

Question 4

____ models describe data at the lowest level. Although seldom used, they capture the features of implementing a database-system.

Answer 4

Physical data models

Question 5

____ uses a group of tables to indicate relationships among those data. Each table contains several columns, and each of them owns a unique name.

Answer 5

Relational Model

Question 6

Data is shown in groups of records in a network database. Relationships are represented by links. The collection of records is structured as a group of arbitrary graphs.

Answer 6

Network Model

Question 7

The ____ is similar to the network model as records and links represent data and relationships among data respectively.

Answer 7

hierarchical model

Question 8

Proposed by Peter P. Chen in 1976; identifies that the real world is composed of entities and their relationships.

Answer 8

Entity- Relationship Model

Question 9

____ is a visual representation of data that describes how data is related to each other.

Answer 9

Entity Relationship Diagram

Question 10

An ____ is any visible object which stores information and can be a person, place, thing, event or a concept; An ____ may be physical or abstract.

Answer 10

Entity

Question 11

____ are the properties of entities which we can use to identify them.

Answer 11

Attributes

Question 12

Types of Attributes

Answer 12

• Key or non-key
• Required or optional
• Simple or composite
• Single-valued and multi-valued
• Stored, Coded or derived

Question 13

An ____ is the structure for the set of entities that share the same structure

Answer 13

entity type

Question 14

the individual entities of a particular entity type are collectively called ____.

Answer 14

entity set

Question 15

Each attribute of an entity type is associated with a ____.

Answer 15

value set

Question 16

This value set is also called ____.

Answer 16

domain

Question 17

The ____ of an attribute is the collection of all possible values an attribute can have.

Answer 17

Domain

Question 18

Any linkage or connection between different entities indicated by a verb is called a ____.

Answer 18

Relationship

Question 19

Each relationship has:

Answer 19

Name, Degree, Cardinality

Question 20

____ refers to the number of entities related to the relationship.

Answer 20

Degree

Question 21

____ is used to depict the connectivity of entities; ____ is the actual number of connected occurrences for each entity.

Answer 21

Cardinality

Question 22

Three Basic Types of Connectivity Relations:

Answer 22

• one-to-one relationship
• **one-to-many **relationship
• many-to-many relationship*

Question 23

The Foreign Key (FK) and only the FK of the related table is the PK of another.

Answer 23

Weak or Non-identifying

Question 24

The FK of the related table is also involved in its PK, along with being the PK of another table

Answer 24

Strong or Identifying

Question 25

To determine relationship ____ , you have to look at it both ways and determine its categorization for each direction.

Answer 25

Participation

Question 26

Participation Types:

When the ‘parent’ does not require a ‘child’ to be present.

Answer 26

Optional

Question 27

Participation Types:

There is an entity required on each end for the relationship to make sense

Answer 27

Mandatory

Question 28

____ is an entity that depends on another entity.

Answer 28

Weak entity

Question 29

____ represents the main characteristic of an Entity.

Answer 29

Key attribute

Question 30

An attribute can also have its own attributes. These attributes are known as ____.

Answer 30

Composite attribute

Question 31

____ is a bottom-up approach in which two lower level entities combine to form a higher level entity.

Answer 31

Generalization

Question 32

_ is opposite to Generalization. It is a top-down approach in which one higher level entity can be broken down into two lower level entities.

Answer 32

Specialization

Question 33

When an Entity is related to itself it is known as ____.

Answer 33

Recursive Relationship