DBMS

11. What is conceptual schema?

The schemas at the view level are called subschema‟s that describe different views of the

database.

12. Define data model?

A data model is a collection of conceptual tools for describing data, data relationships, data

13. What is storage manager?

A storage manager is a program module that provides the interface between the low level data

stored in a database and the application programs and queries submitted to the system.

14. What are the components of storage manager?

The storage manager components include

a) Authorization and integrity manager b) Transaction manager

c) File manager

d) Buffer manager

15. What is the purpose of storage manager?

The storage manager is responsible for the following a) Interaction with the file manager

b) Translation of DML commands in to low level file system commands c) Storing, retrieving and updating data in the database

16. List the data structures implemented by the storage manager . The storage manager implements the following data structure

a) Data files

b) Data dictionary c) Indices

17. What is a data dictionary?

A data dictionary is a data structure which stores meta data about the structure of the database ie. the schema of the database.

18. What is an entity relationship model?

The entity relationship model is a collection of basic objects called entities and relationship among those objects. An entity is a thing or object in the real world that is distinguishable from

other objects.

19. What are attributes? Give examples.

An entity is represented by a set of attributes. Attributes are descriptive properties possessed by

each member of an entity set.

Example: possible attributes of customer entity are customer name, customer id, Customer

Street, customer city.

20. What is relationship? Give examples

A relationship is an association among several entities.

Example: A depositor relationship associates a customer with each account that he/she has.