Note2-ER0 - CSc 134 Database Management and File...

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1 CSc 134 Database Management and File  Organization 2. Entity-Relationship Model Ying Jin Computer Science Department California state University, Sacramento
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2 Database Design Requirement Analysis Conceptual Design Logic Design Physical Design
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3 Entity-Relationship Model Conceptual Model Entity, Relationship ER Diagram
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4 Entity and Attribute Entity An object with a physical existence or conceptual  existence e.g. a person, a company Notation Attributes Properties that describe entities e.g. Name of an employee Notation
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5 Attribute - Simple vs. Composite attribute Simple (atomic) attribute Attribute that are not divisible e.g. SSN, ZIP code Notation Composite Attribute can be divided into smaller subparts e.g. Address Notation
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6 Attribute - Single value vs. Multivaled attribute Single-valued attribute e.g. Age of a person Multivalued attribute e.g. College degree Notation
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7 Attribute - Stored vs. Derived attribute Stored attribute e.g. birthDate Derived attribute Derived from other attribute e.g. age = current date – birthDate Notation
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8 Entity types and entity sets Entity Type Defines a collection of entities that have the same  attributes. e.g. employee describe the  schema  or  intension  for a set of  entities that share the same structure. Entity Set
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This note was uploaded on 02/23/2012 for the course CSC 134 taught by Professor Lee during the Spring '12 term at CSU Chico.

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Note2-ER0 - CSc 134 Database Management and File...

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