BCA3020 – Data Base Management System(DBMS)

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FALL 2015, ASSIGNMENT

PROGRAM	BCA(REVISED FALL 2012)
SEMESTER	3
SUBJECT CODE & NAME	BCA3020 – Data Base Management System(DBMS)
CREDITS	4
BK ID	B1479
MAXIMUM MARKS	60

Answer all the questions

Question. 1. What is data independence? Briefly explain.

Answer:Data independence is the type of data transparency that matters for a centralized DBMS. It refers to the immunity of user applications to changes made in the definition and organization of data. Physical data independence deals with hiding the details of the storage structure from user applications. The application should not be involved with these issues, since there is no difference in the operation carried out against the data. The data independence and operation independence together gives the feature of data abstraction. There are two levels of data independence.

First Level of Data Independence

Question. 2. What is a table in relational data model? List the properties ofrelational tables.

Answer:A relational database is based on the relational model developed by E.F. Codd. A relational database allows the definition of data structures, storage and retrieval operations and integrity constraints. In such a database the data and relations between them are organized into tables. A table is a collection of records and each record in a table contains the same fields. The contents of a table can be permanently saved for future use.

Properties of the relational database model

Properties of Relational Tables:

Question. 3. List and explain the important responsibilities of databasemanager.

Answer:A database manager is responsible for the way a company manages, organises, stores and accesses its information.  It's a role you'll often find in companies that hold a lot of information that needs putting into reports or documents, for example media companies, marketing companies, public sector organisations or financial institutions.

Database manager responsibilities will include:

Question. 4. Explain the Sequential File Organization with the help ofdiagrams.

Answer:Relative data and information is stored collectively in file formats. A file is a sequence of records stored in binary format. A disk drive is formatted into several blocks that can store records. File records are mapped onto those disk blocks.

Question. 5. What is view? List its advantages.

Answer:In a database management system, a view is a way of portraying information in the database. This can be done by arranging the data items in a specific order, by highlighting certain items, or by showing only certain items. For any database, there are a number of possible views that may be specified. Databases with many items tend to have more possible views than databases with few items. Often thought of as a virtual table, the view doesn't actually store information itself, but just pulls it out of one or more existing tables. Although impermanent, a view may be accessed repeatedly by storing its criteria in a query.

Question. 6. Write a note on the following

a) SUBSET Mapping

Answer:In mathematics, the concept of set is fundamental. The modern study of set theory was formalized in the late 1800s. Set theory is a fundamental language of mathematics, and repository of the basic principles of modern mathematics. On the other hand, it’s a branch of mathematics in its own rights, which is

b) SUPERSET Mapping

Answer:A superset is a form of strength training in which you move from one exercise to the next without a rest break.  You can perform supersets in two very different ways and get very different results.

One common form of a superset workout includes working two opposing muscle groups back to back and then repeating the circuit. A common superset includes performing one upper body exercise and immediately move

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