Relational Database model properties - Database

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• Nirja Shah   -Posted on 02 Nov 15
  A Relational Database Model
  - It is based on the relational model developed by E.F. Codd.
  
  - It allows the definition of data structures, storage and retrieval operations and integrity constraints.
  
  - In such a database the data and relations between them are organized into tables.
  
  - A table is a collection of records and each record in a table contains the same fields.
  
  - The contents of a table can be permanently saved for future use.
  
  Properties
  1. Data is presented as a collection of relations.
  
  2. Each relation is depicted as a table.
  
  3. Columns are attributes that belong to the entity modeled by the table (ex. In a student table, you could have name, address, student ID, major, etc.).
  
  4. Each row ("tuple") represents a single entity (ex. In a student table, John Smith, 14 Oak St, 9002342, Accounting, would represent one student entity).
  
  5. Every table has a set of attributes that taken together as a "key" (technically, a "superkey") uniquely identifies each entity (Ex. In the student table, “student ID” would uniquely identify each student – no two students would have the same student ID).

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