Lesson 3 (Week 5)

Question 1

Considered the most popular data model, being simple and easy to understand in nature. Proposed by E.F.Codd in 1970.

Answer 1

Relational Database Model

Question 2

A set of all the possible values an attribute may contain is called a ______.

Answer 2

Domain

Question 3

The _________ key for a given relation is the attribute which uniquely identifies all the records in a relation.

Answer 3

Primary keys

Question 4

A combination of more than one attribute in a relation which can act as a primary key and has a unique identification property is said to be a _________.

Answer 4

Candidate Key

Question 5

Some attributes when combined can have a unique identification property. These attributes when grouped together is a special case called a

Answer 5

Composite Primary Keys

Question 6

Are candidate keys which are not primary keys.

Answer 6

Alternate key

Question 7

It states that no component of a primary key should have a null value.

Answer 7

Entity integrity

Question 8

The _________ constraint states that a value which exists in one relation must also appear for a certain set of attributes in another.

Answer 8

Referential integrity

Question 9

The set of tuples (records/rows) existing in a relation which varies with time is called the ________.

Answer 9

Extension

Question 10

Contrary to the extension of a relation, _________ does not rely on time, and is said to be permanent.

Answer 10

Intension

Question 11

It is caused by the existence of candidate keys.

Answer 11

Key Constraints

Question 12

are caused by the existence of foreign keys.

Answer 12

Referential constraints

Question 13

A lot of other constraints are likely to be used.

Answer 13

Other constraints

Question 13

The _______ approach in the fields of programming, software engineering, database implementation, etc.

Answer 13

object oriented approach

Question 14

An object oriented model includes features such as

Answer 14

objects, inheritance, polymorphism and encapsulation.

Question 15

An object can be any physical entity. It can be a

Answer 15

person, place, thing, or a concept.

Question 16

it refers to a principle where the behavior of a type of object is defined based on the procedures that can be applied to other objects of that type.

Answer 16

Encapsulation

Question 17

It is deriving objects from existing objects. The derived objects acquire properties from their parent object.

Answer 17

inheritance

Question 18

The concept of allowing the same operator name or symbol to be attached to different implementation depending on object types is called _________.

Answer 18

Polymorphism

Question 19

Use logical references (keys) to represent connections between two relations.

Answer 19

Relational Model

Question 20

Use object identifiers (OID) to represent relationships in an ______.

Answer 20

Object-Oriented Model

Question 21

Object oriented systems normally use languages with incorporated _____ such as ____

Answer 21

DML such as C++

data manipulation language