Lovely Professional University 2011 B.Tech Computer Science and Engineering Database management system-assignment 2 - exam paper

PART – B

4. Comment on the significance of administration of a database system. elaborate the different functions associated with database administration?

ANS: A database administrator (DBA) is a person responsible for the design, implementation, maintenance and repair of an organization's database. They are also known by the titles Database Coordinator or Database Programmer, and are closely related to the Database Analyst, Database Modeler, Programmer Analyst, and Systems Manager. The role includes the development and design of database strategies, monitoring and improving database performance and capacity, and planning for future expansion requirements. They may also plan, co-ordinate and implement security measures to safeguard the database. Employing organizations may require that a database administrator have a certification or degree for database.
Database administrator's activities can be listed as below:
• Transferring Data
• Replicating Data
• Maintaining database and ensuring its availability to users
• Controlling privileges and permissions to database users
• Monitoring database performance
• Database backup and recovery
• Database security

5. discuss the concepts of Generalization and Specialization with examples.

ANS:
Generalization: The design process may also proceed in a bottom-up manner, in which multiple entity sets are synthesized into a higher-level entity set on the basis of common features. The database designer may have 1st identified a customer entity set with the attributes name, street, city, and customer-id, and an employee entity set with the attributes name, street, city, employee-id, and salary. There are similarities ranging from the customer entity set and the employee entity set in the sense that they have several attributes in common. This commonality can be expressed by generalization, which is a containment relationship that exists ranging from a higher-level entity set and 1 or more lower-level entity sets. In our example, person is the higher-level entity set and customer and employee are lower-level entity sets.

Specialization: An entity set may include subgroupings of entities that are distinct in a few way from other entities in the set. For instance, a subset of entities within an entity set may have attributes that are not shared by all the entities in the entity set. The E-R model provides a means for representing these distinctive entity groupings. Consider an entity set person, with attributes name, street, and city. A person may be further classified as 1 of the following:
• customer
• employee
every of these person kinds is defined by a set of attributes that includes all the attributes of entity set person plus possibly additional attributes. For example, customer entities may be defined further by the attribute customer-id, whereas employee entities may be defined further by the attributes employee-id and salary. The process of designating subgroupings within an entity set is called specialization. The specialization of person allows us to distinguish among persons according to whether they are employees or customers.

Earning:   Approval pending.