Modern Systems Analysis and Design Chapter 7-9
Data Modeling Concepts
1. Conceptual Data Model: A high-level representation of organizational data structure, independent of
any specific database system.
2. Entity-Relationship Data Model (E-R Model): A detailed logical model depicting entiti...
1. Conceptual Data Model: A high-level representation of organizational data structure, independent of
any specific database system.
2. Entity-Relationship Data Model (E-R Model): A detailed logical model depicting entities, relationships,
and data elements in an organization.
3. Entity-Relationship Diagram (E-R Diagram): A graphical representation of an E-R model.
4. Entity Type: A classification of entities that share common traits.
5. Entity Instance: A single occurrence of an entity type.
6. Attribute: A property or characteristic of an entity of interest to the organization.
7. Candidate Key: An attribute or combination of attributes that uniquely identifies an entity instance.
8. Identifier: A selected candidate key used as the unique identifier for an entity type.
9. Multivalued Attribute: An attribute that can have multiple values for a single entity instance.
10. Repeating Group: A collection of multiple related multivalued attributes.
11. Required Attribute: An attribute that must have a value for every entity instance.
12. Optional Attribute: An attribute that may not have a value for every entity instance.
, 13. Composite Attribute: An attribute made up of meaningful component parts.
14. Derived Attribute: An attribute whose value is calculated from other attributes.
15. Relationship: An association between instances of one or more entity types.
16. Degree: The number of entity types participating in a relationship.
17. Unary Relationship: A relationship occurring within a single entity type (recursive).
18. Binary Relationship: A relationship involving two entity types; the most common form.
19. Ternary Relationship: A simultaneous relationship among three entity types.
20. Cardinality: The number of permissible instances of one entity type associated with another.
21. Associative Entity: An entity that links multiple entity instances and includes relationship-specific
attributes.
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Specialization and Business Rules
1. Subtype: A subgroup of an entity type, possessing distinct attributes or relationships.
2. Supertype: A general entity type that relates to one or more subtypes.
3. Total Specialization Rule: All supertype entities must belong to a subtype.
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