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DBS - Schemas

Aug 2, 2017   # Reading 

ANSI-SPARC Architecture

  • External Level The users’ view of the database. This level describes that part of the database that is relevant to each user.

  • Conceptual Level The community view of the database. This level describes what data is stored in the database and the elationships among the data.

  • Internal Level The physical representation of the database on the computer. This level describes how the data is stored in the database.

Schemas

  • External schemas (subschemas) that correspond to different views of the data.

  • Conceptual schema, which describes all the entities, attributes, and relationships together with integrity constraints.

  • Internal schema, which is a complete description of the internal model, containing the definitions of stored ecords, the methods of representation, the data fields, and the indexes and storage structures used.

To be continued.