CBSE Class XI Informatics Practices Relational Database Management System Notes And Questions
Q 1. What is a database system ? What is its need?
ans. A database is a collection of interrelated data and a database system is basically a computer based recordkeeping system.
A typical file processing system suffers from some major limitations like data redundancy( duplication of data),data inconsistency, unsharable data, unstandardized data, insecure data, incorrect data etc. On the other hand, a database system overcomes all these limitations and ensures continuous efficiency. The advantages provided by a database system are :
(i) Reduced data redundancy
(ii) Controlled data inconsistency
(iii) Shared data
(iv) Standardized data
(v) Secured data
(vi) Integrated data
Therefore, to have the system with increased performance
and efficiency, the database system are preferred.
Q 2. Can you think of disadvantages of using a database system ? What are these ?
ans. With the complex tasks to be performed by database system,
certain things may crop up that may be termed as disadvantages of using database system. These are :
Security maybe compromised without good controls.
2. Extra hardware maybe required.
3. Performance overhead may be significant.
4. System is likely to be complex.
Q 3. A database is to contain information about persons details. At a particular time the following persons are represented in the database,
and their skills are as indicated.
Bhawna Operating and Programming
Chetan Engineering and Programming
David Operating and Engineering
For each person, the database contains various personal details, such as address. For each skill it contains an identification of the appropriate basic training course, an associated job grade code, and other information. The database also contains the date each person attend each course, where applicable ( the assumption is that attendance at the course is essential before the skill can be said to acquired ).
Sketch a relational view for this data.
Q 4. What are views ? How are they useful ?
ans. A view is a virtual table that does not really exist in its own but is
instead derived from one or more underlying base table(s).
The view is a kind of table whose contents are taken upon other
tables depending upon a given query condition. No stored file is created to store contents of a view rather its definition is stored only.
The usefulness of views lies in the fact that they provide an excellent way to give people access to some but not all of the information in a table.
Q 5. What is purpose of using MySQL ?
ans. MySQL is a free, open source Relational Database Management system (RDBMS) that uses Structured Query Language (SQL). In a MySQL database,
information is stored in Tables. A single MySQL database can contain many tables at once and store thousands of individual records.
Q 6. What do you understand by MySQL server instance ?
ans. MySQL server instance is created from background processes
and applications. It stays in memory and listens for client requests coming in over the network and accesses database contents according to those requests and provides that to the clients.
Q 7. What do you understand by MySQL client ?
ans. MySQL Clients are programs that connect to the MySQL server and issue queries in a pre-specified format. MySQL is compatible with the standards based SQL (Structured Query Language). The client program may contact the server programmatically or manually.
Q 8. MySQL provides some command line programs and GUI programs. Name some of these.
ans. Command line programs : mysqldump and mysqladmin
GUI programs: MySQL Administrator and MySQL QueryBrowser
Q 9. What is SQL ? What are different categories of commands available in SQL ?
ans. In order to access data within the Oracle database, all programs an users must use, Structured Query Language (SQL). SQL is the set of
commands that is recognised by nearly all RDBMSs.
SQl commands canbe divided into following categories :
Data Definition Language (DDL) Commands.
2. Transaction Control Language (TCL) commands.
3. Session Control commands.
4. System Control Commands.
Q 10. Differentiate between DDL and SML commands.
ans. The Data Definition Language (DDL) commands, as the name suggests, allow you to perform tasks related to data definition. That is, through these commands, you can perform tasks like, create, alter and drop schema objects, grant and revoke privileges etc.
The Data Manipulation Language (DML) commands,
as the name suggests, are used to manipulate data. That is, DML commands query and manipulate data in existing schema objects.
Originally published at https://kamalsinghstarbooks.xyz on January 6, 2021.