Top 10 DBMS Interview Questions

Top 10 DBMS Interview Questions

 

A list of the top 10  DBMS interview questions and answers is given below.

 

Q1. What is Database?

 

A database is a collection of related data. It is the electronic equivalent of a file cabinet. A database management system (DBMS) or database manager is a program that sets up or structures a database.

 

Q2. What is DBMS? 

 

“A DBMS is a collection of interrelated data and a set of programs to access those data.” DBMS is a system that allows inserting, deleting, and updating databases. DBMS acts as an interface between the application program and the operating system to access or manipulate the database.

 

Q3. What is RDBMS? How is it different from DBMS?

 

A Relational Database Management System (RDBMS) is a database management system that is based on the relational model as introduced by Dr. E.F. Codd.

RDBMS stores data in the form of related tables. An important feature of relational systems is that a single database can be spread across several tables.

Difference between DBMS and RDBMS

 

Q4. What is the main difference between a file processing system and a DBMS?

 

File Management system Like C, C++, Cobol

  1. Small System
  2. The problem of data isolation is found.
  3. Simple Structure.
  4. Single User.
  5. Data Redundancy problem is found.
  6. Few Files.
  7. Often PC-based.
  8. The security of data is not good.
  9. Accessing databases is comparatively difficult.

DBMS Like SQL, Oracle

  1. Large System
  2. The problem of data isolation is not found.
  3. Complex Structure.
  4. Multiple User.
  5. Data Redundancy problem is not found.
  6. Many Users.
  7. Mini Mainframe-based.
  8. Security of data is good.
  9. Accessing databases is easier.

 

Q5. What are super, primary, candidate, and foreign keys?

 

Super Key: A super key is a set of one or more attributes that taken collectively allow us to identify uniquely entities in the entity set.

Primary Key: Primary key can be defined as the maximum no of candidate keys that are chosen by the database designer as the principal means of identifying entities within an entity set. There should not be any duplicacy in the record of a primary key.

Candidate Key: Candidate key can be defined as the minimum no of a super key that identifies record uniquely

Foreign Key: A foreign key is a set of attributes in a table that refers to the primary key of another table.

 

Q6. Applications of DBMS.

 

  •   Banking: This application is very useful for maintaining customer information, accounts and loans, and banking transactions.
  •   Universities: DBMS is used for maintaining student records, course registration, and grades in any university.
  •  Airlines: DBMS is used for reservation and schedule information.
  •  Sales: DBMS is used for customers, products, and purchase information.
  •  Credit Card Transaction: DBMS is used for purchases on credit cards and the generation of monthly statements.

 

Q7. What is the difference between logical data independence and physical data independence?

 

Physical Data Independence: It is the ability to modify the physical schema without having to change the conceptual schema.

Logical Data Independence: It is the ability to modify the conceptual schema without having to change the conceptual schema.

 

Q8. Explain Entity, Attribute, and Domain in DBMS?

 

Entity: It is a “thing” or “object” in the real world that is distinguishable from all other objects.

Attribute: An entity is represented by a set of attributes are descriptive properties possessed by each number of an entity set. Attributes describe the entity to which they are associated.

Domain: The domain of an attribute is the collection of all possible values; an attribute can have.

 

Q9. What are the three levels of data abstraction?

Data Abstraction: The three-level of data abstraction is as follows:

Physical Level: This is the lowest level of abstraction and describes how the data is stored.

Logical Level: This is the next higher level of abstraction and describes what data are store in the database and what relationship exists among those data.

View Level: This is the highest level of abstraction that describes only part of the entire database. The system may provide many views for the same database.

 

Q10. What is the role of a database administrator?

 

Database Administrator: Database Administrator is a technical person responsible for the implementation of data. The job of DBA is to create an actual database and implement the technical control needed by the management level.

 

The role of DBA is:

  1. Storage structure and access method definition.
  2. Schema and physical organization modification.
  3. Granting of authorization for data access.
  4. Routine Maintenance.
  5. Schema Definition.