Database

Tuesday, 21 August 2012

Composite Keys

  • There are the same as primary keys in which they uniquely identify a specific object within the entity.
  • The only difference is that a primary key is just one attribute, while a composite key uses more than one attribute to do the same thing,
  • We underline more than one attribute to show composite keys.
  • unique
  • not null
  • more than one attribute
Posted by Unknown at 00:12
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  • ▼  2012 (44)
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      • Other SELECT commands
      • SELECT with conditions
      • SELECT statement
      • Writing SQL Commands
      • Data Manipulation
      • Structured Query Language
      • Boyce-Codd Normal Form
      • Key Types
      • Improving the Design
      • 2NF to 3NF
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      • 1st Normal Form(1NF)
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      • Data Redundancy
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      • Normalization
      • Data Dictinary
      • Integrity Rules
      • Foreign Key
      • Converting From ERD
      • Converting from ERD
      • Relational Model
      • ERD making tips
      • Composite Entities
      • Super and Sub Type
      • Composite Keys
      • Primary Keys
      • Entity
      • Entity Relationship Diagram(ERD)
      • Basic Modeling Concepts
      • The Database Model
      • Database Design
      • Database Systems Environment
      • DBMS Functions
      • Types of Database
      • Introducing the Database
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