Enhanced entity-relationship modelling concepts. (Lecture 3)

Июль 31, 2022

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Enhanced entity-relationship modelling concepts. (Lecture 3)

Содержание

2. Enhanced Entity-Relationship Modelling Concepts Lecture 3
3. Agenda 1.Relationships with degree higher then 2 2.EER concepts specialisation/generalisation 3.Alternative ER/EER notation
4. 1.Relationships with degree higher then 2 Cardinality Participation Entity Type Occurrence Strong Weak Multiplicity Relationship Type
5. 1.Relationships with degree higher then 2 Degree of a Relationship Number of participating entities in relationship.
6. 1.Relationships with degree higher then 2 Ternary relationship called ‘Registers’
7. 1.Relationships with degree higher then 2 Quaternary relationship called ‘Arranges’
8. 1.Relationships with degree higher then 2 Multiplicity for Complex Relationships Number (or range) of possible occurrences
9. 1.Relationships with degree higher then 2 Ternary relationship called ‘Registers’
10. 1.Relationships with degree higher then 2 Ternary relationship called ‘Registers’ with Values for Staff and Branch
11. 1.Relationships with degree higher then 2 Try to detect multiplicities for remaining participating entities in ternary
12. Agenda 1.Relationships with degree higher then 2 2.EER concepts specialisation/generalisation 3.Alternative ER/EER notation
13. 2.1.The Enhanced Entity-Relationship Model Semantic concepts are incorporated into the original ER model and called the
14. 2.2. Specialisation/Generalisation Superclass An entity type that includes one or more distinct subgroupings of its occurrences.
15. 2.2. Specialisation/Generalisation Superclass/subclass relationship is one-to-one (1:1). Superclass may contain overlapping or distinct subclasses. Not all
16. 2.2. Specialisation/Generalisation Attribute Inheritance An entity in a subclass represents same ‘real world’ object as in
17. 2.2. Specialisation/Generalisation Specialization Process of maximizing differences between members of an entity by identifying their distinguishing
18. 2.2. Specialisation/Generalisation
19. 2.2. Specialisation/Generalisation
20. 2.2. Specialisation/Generalisation
21. 2.2. Specialisation/Generalisation
22. 2.3. Multiplicity constraints in Specialisation/Generalisation Participation constraint Determines whether every member in superclass must participate as
23. 2.3. Multiplicity constraints in Specialisation/Generalisation Disjoint constraint Describes relationship between members of the subclasses and indicates
24. 2.3. Multiplicity constraints in Specialisation/Generalisation
25. 2.3. Multiplicity constraints in Specialisation/Generalisation
26. 2.3. Multiplicity constraints in Specialisation/Generalisation
27. 2.4. EER
28. 2.5. Aggregation Represents a ‘has-a’ or ‘is-part-of’ relationship between entity types, where one represents the ‘whole’
29. 2.6. Composition Specific form of aggregation that represents an association between entities, where there is a
30. Agenda 1.Relationships with degree higher then 2 2.EER concepts specialisation/generalisation 3.Alternative ER/EER notation
31. 3.1. Chen’s ER-diagram notation Meaning ENTITY TYPE WEAK ENTITY TYPE RELATIONSHIP TYPE IDENTIFYING RELATIONSHIP TYPE ATTRIBUTE
32. 3.1. Chen’s ER-diagram notation
33. 3.1. Chen’s ER-diagram notation
34. 3.1. Chen’s ER-diagram notation
35. 3.1. Chen’s ER-diagram notation
36. 3.1. Chen’s ER-diagram notation
37. 3.1. Chen’s ER-diagram notation
39. Скачать презентацию

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Enhanced Entity-Relationship Modelling Concepts
Lecture 3

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Agenda
1.Relationships with degree higher then 2
2.EER concepts specialisation/generalisation
3.Alternative ER/EER notation

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1.Relationships with degree higher then 2
Cardinality
Participation
Entity
Type
Occurrence
Strong
Weak
Multiplicity
Relationship
Type
Occurrence
Degree
Attribute
Complex
Simple
Single valued
Multi valued

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1.Relationships with degree higher then 2
Degree of a Relationship
Number of participating

entities in relationship.
Relationship of degree:
two is binary;
three is ternary;
four is quaternary.

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1.Relationships with degree higher then 2
Ternary relationship called ‘Registers’

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1.Relationships with degree higher then 2
Quaternary relationship called ‘Arranges’

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1.Relationships with degree higher then 2
Multiplicity for Complex Relationships
Number (or

range) of possible occurrences of an entity type in an n-ary relationship when other (n-1) values are fixed.

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1.Relationships with degree higher then 2
Ternary relationship called ‘Registers’

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1.Relationships with degree higher then 2
Ternary relationship called ‘Registers’ with Values

for Staff and Branch Entities Fixed

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1.Relationships with degree higher then 2
Try to detect multiplicities for remaining

participating entities in ternary relationship Registers
Note: You can make appropriate assumptions and detect multiplicities accordingly

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Agenda
1.Relationships with degree higher then 2
2.EER concepts specialisation/generalisation
3.Alternative ER/EER notation

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2.1.The Enhanced Entity-Relationship Model
Semantic concepts are incorporated into the original ER

model and called the Enhanced Entity-Relationship (EER) model.
Examples of additional concepts of EER model are:
specialization / generalization;
aggregation;
composition.

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2.2. Specialisation/Generalisation
Superclass
An entity type that includes one or more distinct subgroupings

of its occurrences.
Subclass
A distinct subgrouping of occurrences of an entity type.

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2.2. Specialisation/Generalisation
Superclass/subclass relationship is one-to-one (1:1).
Superclass may contain overlapping or

distinct subclasses.
Not all members of a superclass need to be a member of a subclass.

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2.2. Specialisation/Generalisation
Attribute Inheritance
An entity in a subclass represents same ‘real world’

object as in superclass, and may possess subclass-specific attributes, as well as those associated with the superclass.

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2.2. Specialisation/Generalisation
Specialization
Process of maximizing differences between members of an entity

by identifying their distinguishing characteristics.
Generalization
Process of minimizing differences between entities by identifying their common characteristics.

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2.2. Specialisation/Generalisation

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2.2. Specialisation/Generalisation

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2.2. Specialisation/Generalisation

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2.2. Specialisation/Generalisation

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2.3. Multiplicity constraints in Specialisation/Generalisation
Participation constraint
Determines whether every member in superclass

must participate as a member of a subclass.
May be mandatory (total) or optional.

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2.3. Multiplicity constraints in Specialisation/Generalisation
Disjoint constraint
Describes relationship between members of

the subclasses and indicates whether member of a superclass can be a member of one, or more than one, subclass.
May be disjoint (OR) or overlapping (AND)

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2.3. Multiplicity constraints in Specialisation/Generalisation

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2.3. Multiplicity constraints in Specialisation/Generalisation

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2.3. Multiplicity constraints in Specialisation/Generalisation

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2.4. EER

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2.5. Aggregation
Represents a ‘has-a’ or ‘is-part-of’ relationship between entity types, where

one represents the ‘whole’ and the other ‘the part’.

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2.6. Composition
Specific form of aggregation that represents an association between entities,

where there is a strong ownership and coincidental lifetime between the ‘whole’ and the ‘part’.

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Agenda
1.Relationships with degree higher then 2
2.EER concepts specialisation/generalisation
3.Alternative ER/EER notation

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3.1. Chen’s ER-diagram notation
Meaning
ENTITY TYPE
WEAK ENTITY TYPE
RELATIONSHIP TYPE
IDENTIFYING RELATIONSHIP TYPE
ATTRIBUTE
KEY ATTRIBUTE
MULTIVALUED

ATTRIBUTE
COMPOSITE ATTRIBUTE
DERIVED ATTRIBUTE
TOTAL PARTICIPATION OF E2 IN R
CARDINALITY RATIO 1:N FOR E1:E2 IN R
STRUCTURAL CONSTRAINT (min, max) ON PARTICIPATION OF E IN R

Symbol

(min,max)

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3.1. Chen’s ER-diagram notation

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3.1. Chen’s ER-diagram notation

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3.1. Chen’s ER-diagram notation

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3.1. Chen’s ER-diagram notation

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3.1. Chen’s ER-diagram notation

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Enhanced entity-relationship modelling concepts. (Lecture 3)

Содержание

Enhanced Entity-Relationship Modelling ConceptsLecture 3

Agenda1.Relationships with degree higher then 22.EER concepts specialisation/generalisation3.Alternative ER/EER notation

1.Relationships with degree higher then 2CardinalityParticipationEntity TypeOccurrenceStrongWeakMultiplicityRelationshipTypeOccurrenceDegreeAttributeComplexSimpleSingle valuedMulti valued

1.Relationships with degree higher then 2Degree of a RelationshipNumber of participating

1.Relationships with degree higher then 2Ternary relationship called ‘Registers’

1.Relationships with degree higher then 2Quaternary relationship called ‘Arranges’

1.Relationships with degree higher then 2Multiplicity for Complex Relationships Number (or

1.Relationships with degree higher then 2Ternary relationship called ‘Registers’

1.Relationships with degree higher then 2Ternary relationship called ‘Registers’ with Values

1.Relationships with degree higher then 2Try to detect multiplicities for remaining

Agenda1.Relationships with degree higher then 22.EER concepts specialisation/generalisation3.Alternative ER/EER notation

2.1.The Enhanced Entity-Relationship ModelSemantic concepts are incorporated into the original ER

2.2. Specialisation/GeneralisationSuperclassAn entity type that includes one or more distinct subgroupings

2.2. Specialisation/GeneralisationSuperclass/subclass relationship is one-to-one (1:1). Superclass may contain overlapping or

2.2. Specialisation/GeneralisationAttribute InheritanceAn entity in a subclass represents same ‘real world’

2.2. Specialisation/GeneralisationSpecialization Process of maximizing differences between members of an entity

2.2. Specialisation/Generalisation

2.2. Specialisation/Generalisation

2.2. Specialisation/Generalisation

2.2. Specialisation/Generalisation

2.3. Multiplicity constraints in Specialisation/GeneralisationParticipation constraintDetermines whether every member in superclass

2.3. Multiplicity constraints in Specialisation/GeneralisationDisjoint constraint Describes relationship between members of

2.3. Multiplicity constraints in Specialisation/Generalisation

2.3. Multiplicity constraints in Specialisation/Generalisation

2.3. Multiplicity constraints in Specialisation/Generalisation

2.4. EER

2.5. AggregationRepresents a ‘has-a’ or ‘is-part-of’ relationship between entity types, where

2.6. CompositionSpecific form of aggregation that represents an association between entities,

Agenda1.Relationships with degree higher then 22.EER concepts specialisation/generalisation3.Alternative ER/EER notation

3.1. Chen’s ER-diagram notationMeaningENTITY TYPEWEAK ENTITY TYPERELATIONSHIP TYPEIDENTIFYING RELATIONSHIP TYPEATTRIBUTEKEY ATTRIBUTEMULTIVALUED

3.1. Chen’s ER-diagram notation

3.1. Chen’s ER-diagram notation

3.1. Chen’s ER-diagram notation

3.1. Chen’s ER-diagram notation

3.1. Chen’s ER-diagram notation

3.1. Chen’s ER-diagram notation

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Enhanced Entity-Relationship Modelling Concepts
Lecture 3

Agenda
1.Relationships with degree higher then 2
2.EER concepts specialisation/generalisation
3.Alternative ER/EER notation

1.Relationships with degree higher then 2
Cardinality
Participation
Entity
Type
Occurrence
Strong
Weak
Multiplicity
Relationship
Type
Occurrence
Degree
Attribute
Complex
Simple
Single valued
Multi valued

1.Relationships with degree higher then 2
Degree of a Relationship
Number of participating

1.Relationships with degree higher then 2
Ternary relationship called ‘Registers’

1.Relationships with degree higher then 2
Quaternary relationship called ‘Arranges’

1.Relationships with degree higher then 2
Multiplicity for Complex Relationships
Number (or

1.Relationships with degree higher then 2
Ternary relationship called ‘Registers’

1.Relationships with degree higher then 2
Ternary relationship called ‘Registers’ with Values

1.Relationships with degree higher then 2
Try to detect multiplicities for remaining

Agenda
1.Relationships with degree higher then 2
2.EER concepts specialisation/generalisation
3.Alternative ER/EER notation

2.1.The Enhanced Entity-Relationship Model
Semantic concepts are incorporated into the original ER

2.2. Specialisation/Generalisation
Superclass
An entity type that includes one or more distinct subgroupings

2.2. Specialisation/Generalisation
Superclass/subclass relationship is one-to-one (1:1).
Superclass may contain overlapping or

2.2. Specialisation/Generalisation
Attribute Inheritance
An entity in a subclass represents same ‘real world’

2.2. Specialisation/Generalisation
Specialization
Process of maximizing differences between members of an entity

2.3. Multiplicity constraints in Specialisation/Generalisation
Participation constraint
Determines whether every member in superclass

2.3. Multiplicity constraints in Specialisation/Generalisation
Disjoint constraint
Describes relationship between members of

2.5. Aggregation
Represents a ‘has-a’ or ‘is-part-of’ relationship between entity types, where

2.6. Composition
Specific form of aggregation that represents an association between entities,

Agenda
1.Relationships with degree higher then 2
2.EER concepts specialisation/generalisation
3.Alternative ER/EER notation

3.1. Chen’s ER-diagram notation
Meaning
ENTITY TYPE
WEAK ENTITY TYPE
RELATIONSHIP TYPE
IDENTIFYING RELATIONSHIP TYPE
ATTRIBUTE
KEY ATTRIBUTE
MULTIVALUED