Principles Of Conceptual Database Design

Question 1

Model

Answer 1

A representation of reality that retains only selected details.

Question 2

Map

Answer 2

To associate elements in one sphere with elements in an other sphere.

Question 3

Object-Oriented-Model

Answer 3

A model representing real world entities as objects rather than records.

Question 4

Semantic model

Answer 4

A model that captures the meanings of real world entities and relationships.

Question 5

Object Set

Answer 5

A set of things of the same kind.

Question 6

Object Instance

Answer 6

A particular member of an object set.

Question 7

Lexical Object Set

Answer 7

An object set consisting of instances that can be printed.

Question 8

Abstract object set

Answer 8

An object set consisting of instances that cannot be printed.

Question 9

Surrogate key

Answer 9

A unique computer system identifier for an abstract object instance. it has no meaning outside the computer system.

Question 10

Specialization

Answer 10

An object set is a subset of another object set.

Question 11

Generalization

Answer 11

An object set that is a superset of(or contains) another object set.

Question 12

Relationship

Answer 12

A linking between instances of two object sets.

Question 13

Aggregate Object Set

Answer 13

A relationship viewed as an object set.

Question 14

Cardinality

Answer 14

The maximum number of instances of one object set related to a single instance of the other object set.

Question 15

A Functional Relationship

Answer 15

A relationship having a maximum cardinality o one in at least one direction.

Question 16

One to One

Answer 16

Relationship cardinalities of one in both directions.

Question 17

One to Many

Answer 17

Relationship cardinalities of one in one direction and many in the other.

Question 18

Many to Many

Answer 18

Relationship cardinalities of many in both directions.

Question 19

Attribute

Answer 19

Functional relationship from an object set to another set.

Question 20

Null attribute value

Answer 20

An attribute value that does not exist for a specific object instance.

Question 21

Key

Answer 21

A value that can always be used to uniquely identify an object instance.

Question 22

External Key

Answer 22

A set of lexical attributes whose values always identify a single object instance.

Question 23

Identifier

Answer 23

An external key

Question 24

Inherit

Answer 24

The property of a specialization set that causes it to have all the attributes of its generalization set.

Question 25

Conceptual Object Set

Answer 25

An object set whose instances are conceptual objects.

Question 26

Physical Object Set

Answer 26

An object set whose instances are physical objects.

Question 27

Dependent Object Set

Answer 27

An object set whose instances must be related to at least one other instance of another object set.

Question 28

View

Answer 28

A definition of a restricted portion of the database.