18CS54 : dbms
8 Mar 2023
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Document Summary
Three schema architecture, the goal of the three-schema architecture is to separate the user applications from the physical database. The internal level: has an internal schema, describes the physical storage structure of the database, uses a physical data model and describes the complete details of data storage and access paths for the database. Self-describing nature of a database system: a fundamental characteristic of the database approach is the database system contains not only database itself but also a complete definition or description of the database structure or constrains. By contrast, dbms access programs do not require such changes in most cases. The structure of data files is stored in the. Some users may not need to be aware of whether the data they refer to is stored or derived: a multiuser dbms whose users have a variety of applications must provide facilities for defining multiple views.
