DBMS Interview Questions - Part 2

DBMS Interview Questions - Part 2

Click Here - For DBMS Interview Questions - Part 1

What is a database system?

- The collection of database and DBMS software together is known as a database system.

What do you mean by Data Modelling ?

- Data Modelling is the set of conceptual tools for describing data relationship, data semantics, and consistency constraints. Different data models are : Network model, Relational model, Object Oriented model, ER model, and more.

Explain RDBMS ?

- RDBMS stands for Relational Database Management System. It arranges information into allied rows and columns. RDMS is an information management system which is oriented on a data model. RDBMS Example systems are SQL Server, Oracle, MySQL, MariaDB and SQLite.

Explain Abstraction of Data, with reference to DBMS ?

- Data Abstraction refers to the process of hiding background details from user.

Explain the 3 L’s of Data Abstraction ?

- It refers to three levels of abstraction. They are :

1. Physical Level : It is lowest level of abstraction. It describes how data is actually stored. It also describes complex data structure in detail.

2. Logical Level : It describes what data get stored in the database and what are the relationships among them.

3. View Level : It is the highest level of data abstraction that only describes a part of database indirectly.

What are the disadvantages of using Flat File System ?

1. Data Redundancy and Inconsistency.
2. Difficulty in accessing data.
3. Data Isolation.
4. Integrity Problem.
5. Security Issues.

What is Database Schema ?

- Schema refers to the overall structure of database without data values.

What do you mean by transparent DBMS?

- The transparent DBMS is a type of DBMS which keeps its physical structure hidden from users.

Explain ER Model ?

- This model is based on the perception of real world that consists of collection of basic entities and relationship among these objects. It is the graphical representation of the database.

What do you understand by Data Independency ?

- It refers to the capacity to change data at one level without affecting next higher level is called Data Independence. It is of two types : Physical DI, Logical DI.

Physical DI : It indicates that physical storage of device could be changed without affecting conceptual view.

Logical DI : It indicates that conceptual schema can be changed without affecting existing external schema

What is a Database Language ?

- Database Language is a medium by which we can interact with the database system through some set of commands. These commands are structured.

What are different types of database languages ?

1. DDL : Data Definition Language defines different structures in database.
   Example – create, alter, drop, truncate are some DDL commands.
   
   
2. DML : Data Manipulation Language allows database user to manipulate data.
   Example – insert, insert into, update, delete, select are DML commands.
   
   
3. TCL : Transaction Control Language commands are used to manage transactions in the database.
   Example – commit, rollback, savepoint are TCL commands.
   
   
4. DCL : Data Control Language is used to control access to data stored in a database.
   Example – Grant, Revoke are DCL commands.