data modeling

Data modeling - An Introduction to Systems Modeling&#2 Systems Modeling Logical models(DFDs ERDs Physical models(Technology dependent Data

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Unformatted text preview: An Introduction to Systems Modeling  Systems Modeling Logical models (DFDs, ERDs) Physical models (Technology dependent) Data Modeling Data Modeling A technique for organizing and documenting a system’s DATA D Data models are much smaller than process and object models and can be constructed more rapidly Entity Relationship Diagram (ERD). D An ERD depicts data in terms of the entities and relationships described by the data. System Concepts for Data Modeling  Data is a resource to be shared by many users (interrelating organizational components) y Data must be organized in a way that is flexible to allow for access by: D different users D running different applications D at different locations D on different platforms Sample Conceptual Data Model System Concepts for Data Modeling  Entities An entity is a class of: Persons (customers, students, employees), Places (plant, warehouse, Washington,D.C.) Objects (drill, automobiles, work stations/computers) Events (application, flight, invoice, order, sale, trip) Concepts (account, bond, course, fund) about which we need to capture and store data. System Concepts for Data Modeling  Attributes An attribute is a descriptive property or characteristic of an entity. Synonyms include element , property , and field . Some attributes can be logically grouped into super-attributes or compound attributes. S T U D E N T N a m e . L a s t N a m e . F ir s t N a m e . M id d le In itia l A d d r e s s . S tr e e t A d d r e s s . C ity . S ta te o r P r o v in c e . C o u n try . P o s ta l C o d e P h o n e N u m b e r . A r e a C o d e . E x c h a n g e N u m b e r . N u m b e r W ith in E x c h a n g e D a te o f B ir th G e n d e r R a c e M a jo r G r a d e P o in t A v e r a g e A ttrib u te s a n d c o m p o u n d a ttrib u te s Entity instance: a single occurrence of an entity....
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This note was uploaded on 02/28/2011 for the course BMGT 407 taught by Professor Staff during the Spring '08 term at Maryland.

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Data modeling - An Introduction to Systems Modeling&#2 Systems Modeling Logical models(DFDs ERDs Physical models(Technology dependent Data

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