BCA 5th Sem Most Important Questions Of Introduction Of DBMS

BCA 5th Sem Most Important Questions Of Introduction Of DBMS

Here are precise answers to your questions based on a standard DBMS syllabus, which aligns well with the CCSU curriculum:

1. What do you mean by DBMS?

A Database Management System (DBMS) is software that enables users to define, create, maintain, and manage data in a database. It ensures efficient data organization, storage, and retrieval while providing features like data security and concurrent access.

2. What do you mean by DML and DDL?

DML (Data Manipulation Language): Commands used to manipulate data in the database. Examples: SELECT, INSERT, UPDATE, DELETE.
DDL (Data Definition Language): Commands used to define or modify the database structure. Examples: CREATE, ALTER, DROP.

3. Advantages and Disadvantages of DBMS

Advantages:

Data consistency and integrity.
Easy data sharing among multiple users.
Data security and authorization mechanisms.
Backup and recovery.
Reduced data redundancy.

Disadvantages:

High initial cost of hardware and software.
Complexity in implementation and management.
Requires skilled personnel.
Performance overhead in large-scale databases.

4. What are attributes? Give examples.

Attributes represent the properties or characteristics of an entity in a database.
Example:

Entity: Student
Attributes: Student_ID, Name, Age, Course.

5. Define Primary Key, Not Null Key, and Unique Key

Primary Key: A unique identifier for each record in a table. Cannot be null.
Example: Student_ID.
Not Null Key: Ensures a column cannot have NULL values.
Example: Name.
Unique Key: Ensures all values in a column are unique but allows one NULL.
Example: Email.

6. What are anomalies in 1NF?

1NF anomalies arise when:

Data is not atomic (e.g., storing multiple phone numbers in one field).
Redundancy increases chances of update, insert, and delete anomalies.

7. Explain ER Diagram

An Entity-Relationship Diagram (ERD) is a visual representation of entities, their attributes, and relationships in a database.

Entities: Objects or items (e.g., Student).
Attributes: Characteristics (e.g., Name, ID).
Relationships: Connections between entities (e.g., Student enrolls in Course).

8. Briefly explain security and authorization.

Security: Protecting data against unauthorized access.
Authorization: Granting permissions to users to access specific data or operations.

9. What do you mean by referential integrity?

It ensures consistency of relationships between tables. A foreign key in one table must correspond to a primary key in another table or be NULL.

10. Explain Hashing in brief.

Hashing is a technique for mapping data to a fixed-size value (hash code) to enable fast access. It's commonly used in indexing.

11. What are the pitfalls of lock-based protocols?

Deadlock: Two transactions wait indefinitely for each other.
Starvation: A transaction never gets access due to high-priority transactions.
Overhead: Managing locks increases system load.

12. Explain specialization and generalization in ER diagram with examples.

Specialization: Dividing an entity into sub-entities based on attributes.
Example: Employee → Manager, Engineer.
Generalization: Combining sub-entities into a single generalized entity.
Example: Car, Bike → Vehicle.

13. What do you understand by RDBMS? Difference between DBMS and RDBMS.

RDBMS (Relational DBMS): A DBMS that stores data in tables (relations). Example: MySQL.

Difference:

DBMS lacks relations, while RDBMS uses tables with keys.
RDBMS supports SQL and ensures ACID properties.

14. Define Normal Forms

1NF: Atomic data, no repeating groups.
2NF: 1NF + No partial dependency.
3NF: 2NF + No transitive dependency.

15. Characteristics of SQL & Aggregate Functions

Characteristics:

Declarative language.
Standardized commands.
Can manage large datasets.

Aggregate Functions:

COUNT(): Counts rows.
Example: COUNT(*).
SUM(): Adds values.
Example: SUM(Salary).
AVG(): Calculates average.
Example: AVG(Age).
MAX(): Finds max value.
Example: MAX(Marks).
MIN(): Finds min value.
Example: MIN(Price).

16. Explain superclass, inheritance, and generalization with examples.

Superclass: A general entity.
Example: Vehicle.
Inheritance: Subclasses inherit superclass attributes.
Example: Car, Bike inherit Vehicle.
Generalization: Combining subclasses into a superclass.

17. What is a transaction? State diagram

A transaction is a unit of work that must be executed completely or rolled back.

State Diagram:

States:

Active
Partially committed
Committed
Failed
Aborted

18. Define E-R Diagram & Example (Library Management)

An E-R Diagram is a conceptual data model using entities, attributes, and relationships.

Library Management System Example:

Entities: Book, Member, Librarian.
Attributes: Book_ID, Name, Issue_Date.

19. Who are data administrators? Functions of DBAs

Data Administrator: Manages database policies, design, and architecture.
DBA Functions:
1. Backup and recovery.
2. Performance tuning.
3. Security management.

20. Short Notes

i) Strong and Weak Entity:

Strong Entity: Exists independently. Example: Employee.
Weak Entity: Depends on a strong entity. Example: Dependent.

ii) Different levels of data abstraction:

Physical Level: How data is stored.
Logical Level: Structure of the database.
View Level: User interface.

iii) Database Recovery Techniques:

Log-based recovery.
Shadow paging.
Checkpoints.

NOTE :
This is an expected question answer which you have appeared in most of the exams. You will be able to study chapterwise most important topics as per your knowledge and will not be afraid of giving the paper. This is a great tool to improve your preparation.
The answers which are given in short cut or less words, here you can write and read them according to your understanding.