'M relationship' diaporamas de présentation

Chapter 5: Relational Database

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Data Modeling with ERD

Data Modeling with ERD. ISYS 363. Entities. An entity is a person, place, object, event, or concept in the user environment about which the organization wishes to maintain data. Person: Employee, Student, patient Place: Warehouse, Store Object: Product, Machine.

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Database Design Using Entity-Relationship Models

Database Design Using Entity-Relationship Models. Mapping E-R models into relations Four common data structures. Mapping E-R Models to Tables. We may not be familiar with all notations There may be E-R constructs that cannot be translated directly Multi-valued attributes

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The One-to-Many Relationship

The One-to-Many Relationship. Cow of many-well milked and badly fed Spanish proverb. The one-to-many relationship. Entities are related to other entities A 1:m relationship. Hierarchical relationships. Occur frequently Multiple 1:m relationships. FIRM. DIVISION. DEPARTMENT. SECTION.

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SA0951a Entity-Relationship Modelling

SA0951a Entity-Relationship Modelling. What is it about?. ER model is used to show the C onceptual schema of an organisation. Independent of specific data model or DBMS The model is later transformed into a Logical model (e.g. relational) on which the physical database is built

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Entity Relationships

Entity Relationships. A337. Data Stores-Specific Diagrams. Included on both Flowcharts and DFDs There are also rules related to data stores. For example Can there be multiple invoices with the same number? Can a customer have more than one address?

338 views • 17 slides