Describe ansi sparc 3 level architecture of dbms and details of languages associated at differentlevels plusthe level of data independence?

Answer 1

The ANSI-SPARC Architecture (American National Standards Institute, Standards Planning And Requirements Committee) is an abstract design standard for a DBMS, first proposed in 1975. Most modern commercial DBMS are based on this system. The ANSI-SPARC model never became a formal standard. The objective of the three-level architecture is to separate the users' view(s) of the database from the way that it is physically represented. This is desirable since: * It allows independent customised user views. ** Each user should be able to access the same data, but have a different customised view of the data. These should be independent: changes to one view should not affect others. * It hides the physical storage details from users.

** Users should not have to deal with physical database storage details. They should be allowed to work with the data itself, without concern for how it is physically stored. * The database administrator should be able to change the database storage structures without affecting the users' views. ** From time to time rationalisations or otherchanges to the structure of an organisation's data will be required. * The internal structure of the database should be unaffected by changes to the physical aspects of the storage. ** For example, a changeover to a new disk. * The database administrator should be able to change the conceptual or global structure of the database without affecting the users.

** This should be possible while still maintaining the desired individual users' views. with kind regards M I K