Q.1 Briefly discuss the different layers of ANSI SPARC architecture.
Ans: The three layers of ANSI SPARC architecture are like this:
1. Internal view is at the lowest level of abstraction, closest to the physical storage method employed. It points out how the data will be stored and explains the data structures and access methods to be employed by the database. There is one internal view for the whole database.
2. Global or Conceptual View: At this level of abstraction all the database entities and the relationships between them are included. There is one conceptual view for the whole database.
3. External or User View: The external or user view is at the highest level of database abstraction in which just only those portions of the database concern to a user or application programme are involved. Some external or user views may exist for a specified global or conceptual view.