OMIS 2000 Data Modelling 4of5

OMIS 2000 Data Modelling 4of5 - OMIS 2000 Information...

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Unformatted text preview: 1 Information Systems – Data Analytics Modeling Organizational Data Lecture 4 of 5 Multiple Relationships & Associative Entities OMIS 2000 2 ER diagrams Focus on data which is at the base of an IS Provides a conceptual data model The model can be easily extended to provide a physical design for the system’s DB “An Entity-Relationship model is a detailed, logical representation of the data for an organization or for a business area. It is expressed using an ER diagram.” (source: Hoffer et al., 2002) 3 E-R Model Constructs E-R Model Constructs Entities: Entities: Entity instance–person, place, object, event, concept (often Entity instance–person, place, object, event, concept (often corresponds to a row in a table) corresponds to a row in a table) Entity Type–collection of entities (often corresponds to a table) Entity Type–collection of entities (often corresponds to a table) Relationships: Relationships: Relationship instance–link between entities (corresponds to Relationship instance–link between entities (corresponds to primary key-foreign key equivalencies in related tables) primary key-foreign key equivalencies in related tables) Relationship type–category of relationship…link between entity Relationship type–category of relationship…link between entity types types Attribute– Attribute– property or characteristic of an entity or relationship type property or characteristic of an entity or relationship type (often corresponds to a field in a table) (often corresponds to a field in a table) 4 Attributes Attributes...
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  • Fall '13
  • hk
  • Entity-relationship model, associative entity, Multiple Relationships

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