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gis > ERD > Flashcards

ERD Flashcards

1
Q

A thing in the real world with an independent existence (house, person

A

Entity

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2
Q

May be an object with physical existence or with a consensual existence (course, job)

A

Entity

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3
Q

Properties that describe the entities

A

Attributes

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4
Q

TYPES OF ATTRIBUTES

A

Composite attributes
Simple attributes
Single valued attributes
Multivalued attributes
Derived attributes
Stored attributes

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5
Q

Can be divided into further parts

A

Composite attributes

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6
Q

Cannot be divided further

A

Simple attributes

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7
Q

Have a single value for a particular entity

A

Single valued attributes

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8
Q

Can have set of values for a particular entity

A

Multivalued attributes

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9
Q

Can be derived from other attributes

A

Derived attributes

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10
Q

From which the value of other attributes are derived

A

Stored attributes

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11
Q

Has multivalued and composite components in it

A

Complex attributes

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12
Q

Multivalued attributes represented within

A

{ }

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13
Q

Composite values represented within

A

( )

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14
Q

Something not applicable or unknown

A

Null values

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15
Q

Collection of entities that have the same attributes

A

Entity types

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16
Q

Collection of entities of a particular entity type at a point in time

A

Entity set

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17
Q

Attribute that is capable of identifying each entity uniquely

A

Key attribute

18
Q

The set of values that can be assigned to an attribute

A

Value set of attributes

19
Q

database design process

A
  1. requirements collection and analysis
  2. conceptual design
  3. logical design (data model mapping)
  4. physical design
20
Q

Database designers understand and document the data requirements of the database users

A

Requirements collection and analysis

21
Q

Consists of user-defined operations

A

Functional requirements

22
Q

Creating conceptual schema

A

Conceptual design

23
Q

Concise description of the data requirements and detailed descriptions of the entity types relationships and constraints

A

conceptual schema

24
Q

Actual implementation of the database, using commercial DBMS

A

Logical design (data model mapping)

25
Q

The internal storage structures, indexes, access paths are specified

A

Physical design

26
Q

Do not key attributes of their own

A

WEAK ENTITY TYPES

27
Q

Identified by relating to another entity type called the identifying or the owner entity type

A

WEAK ENTITY TYPES

28
Q

Relationship between weak entity type to its owner

A

Identifying relationship

29
Q

different symbols used in erd

A

entity
weak entity
attributes
key attribute
multivalued attribute
composite attribute
derived attribute
identifying relationship

30
Q

Association among 2 or more entities

A

Relationship

31
Q

Denotes the number of entity types that participate in a relationship

A

Degree of relationship

32
Q

degrees of relationship

A

unary relationship
binary relationship
ternary relationship

33
Q

relationship constraints

A

cardinality ration
participation constraints

34
Q

maximum number of relationship instances that can entity can participate in (1:1, 1:N, N:1, M:N)

A

Cardinality ratio

35
Q

specifies whether existence of an entity depends on its being related to another entity

A

Participation constraints

36
Q

2 types of participation

A

total participation
partial participation

37
Q

attributes of relationship types

A

1:1
- 1:1
1:N
M:N

38
Q

Signifies the role that a participating entirety plays in each relationship instance

A

Role names

39
Q

Same entity type participates more than once in a relationship type in different roles

A

Recursive relationships

40
Q

enhanced er model

A

generalization
specialization

41
Q

Bottom up approach where two lower level entities combine to form a higher level entity

A

Generalization

42
Q

Top down approach where it defines set of subclasses on an entity type

A

Specialization

gis (4 decks)

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