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.