354.ERModel - DatabaseSystemsI TheEntityRelationshipModel

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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  1 Database Systems I  The Entity-Relationship Model
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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  2 Overview of Database Development Requirements Analysis What data are to be stored in the enterprise? What are the required applications? What are the most important operations? High-level database design What are the  entities  and  relationships  in the enterprise? What information about these entities and relationships  should we store in the database? What are the  integrity constraints  or  business rules  that  hold? ER model or UML to represent high-level design
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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  3 Overview of Database Development Conceptual database design What data model to implement the DBS? E.g., relational data model Map the high-level design (e.g., ER diagram) to a (conceptual)  database schema of the chosen data model. Physical database design What DBMS to use? What are the typical workloads of the DBS? Build indexes to support efficient query processing. What redesign of the conceptual database schema is necessary  from the point of view of efficient implementation?
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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  4 Overview of Database Development Requirements Analysis / Ideas High-Level Database Design Conceptual Database Design / Relational Database Schema Physical Database Design / Relational DBMS Similar to software development
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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  5 Entity-Relationship Model Short: ER model. A lot of similarities with other modeling languages  such as UML. Concepts  Entities / Entity sets, Attributes, Relationships/ Relationship sets, and Constraints. Offers more modeling concepts than the relational  data model (which only offers relations). Closer to the way in which people think.
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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  6 Entity-Relationship Diagrams An  Entity-Relationship diagram  ( ER diagram ) is a  graph with nodes representing entity sets, attributes  and relationship sets. Entity sets denoted by  rectangles . Attributes denoted by  ovals . Relationship sets denoted by  diamonds . Edges ( lines ) connect entity sets to their attributes and  relationship sets to their entity sets.
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CMPT 354, Simon Fraser University, Fall 2008, Martin Ester  7 Entities and Entity Sets Entity:   Real-world object  distinguishable  from  other objects, e.g. employee Miller.  Entity can be physical or abstract object. An entity is associated with 
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This note was uploaded on 10/07/2009 for the course CS 12601 taught by Professor Kewang during the Spring '09 term at Simon Fraser.

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354.ERModel - DatabaseSystemsI TheEntityRelationshipModel

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