7. Define the "integrity rules"?
There are two Integrity rules.
8. What is extension and intension?
9. What is System R? What are its two major subsystems?
System R was designed and developed over a period of 1974-79 at IBM San Jose Research Center. It is a prototype and its purpose was to demonstrate that it is possible to build a Relational System that can be used in a real life environment to solve real life problems, with performance at least comparable to that of existing
10. How is the data structure of System R different from the relational structure?
Unlike Relational systems in System R
11. What is Data Independence?
Data independence means that "the application is independent of the storage structure and access strategy of data". In other words, The ability to modify the schema definition in one level should not affect the schema definition in the next higher level.
12. What is a view? How it is related to data independence?
A view may be thought of as a virtual table, that is, a table that does not really exist
in its own right but is instead derived from one or more underlying base table. In
other words, there is no stored file that direct represents the view instead a
definition of view is stored in data dictionary.