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.
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.