Database Management System - B.C.A 18 - 20 Sem 2 Feb 2019

SAINTGITS COLLEGE OF APPLIED SCIENCES

First Internal Assessment Examination, March 2019

Department of BCA    , Semester II

Database Management Systems (Core)

ANSWER SHEME

SECTION A

1.          The database catalog of a database instance consists of metadata in which definitions of database objects such as base tables, views (virtual tables), synonyms, value ranges, indexes, users, and user groups are stored

2.          A database management system (DBMS) is system software for creating and managing databases.

3.          Entity is an object that has physical or logical existence Eg: a particular student

4.          Schema means structure of a database and Instances means content of database at a particular time.

5.          Create table student(regno varchar(2) primary key, name varchar(20),age int, contactno varchar(20));

6.          Primary key is used for uniquely identifying data in a table

Foreign key is used for linking two tables.

SECTION B

7.          Data model:- collection of concepts that can be used to describe structure of a database.

a.           High level datamodel:-It uses concept such as entity,attribute and relationship for describing structure of a database

b.           Logical datamodel-

c.           Lowlevel datamodel- physicat structure such as access path, indexing etc.

8.          A. Self-describing nature of a database

b. Insulation between programs and data

c. Support of multiple views

d. Sharing of data and multiuser transaction processing

9.          Capacity to change the schema at one level without changing higher lavel

1.           Logical data independence:-capacity to change conceptual schema without changing external schema

2.           Physical data independence:- capacity to change physical schema without changing conceptual schema

10.        DDL: create, alter, drop

DML:-Insert, delete, update

11.        Numeric type:- INT,smallint,float,decimal(p,s), number(p,s)

Character type:-char,varchar(20)

Bit string type:- Bit,bitvarying(20), BLOB

Time

Date

Timestamp

12.        UNION,INTERSECT

EXCEPT

SECTION C

13.        A. Self-describing nature of a database

b. Insulation between programs and data

c. Support of multiple views

d. Sharing of data and multiuser transaction processing

e. Controlling redundancy

f. provide persistant storage for program object

g. Restricting unauthorized access

h.providing backup and recovery

i. Providing multiple userinterface

j. Representing complex relationship among data

14.        Draw picture(5 marks)

Explain different user interfaces

DBA uses DDL commands to define structure of the database and DDL compiler compiles the DDL statements and store result in system catalogue. DBA can also communicate with database using privileged commands.

Casual users communicate database using dml statements, DML compiler convert entered information in to an internal form, precompiler eliminate redundancy and convert the code in to an executable form and give it to runtime database processor.

Runtime database processor works with stored data manager which in turn uses the basic operating system services for carrying out low level input output operations between disk and main memory.

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