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dbms Interview Questions and Answers

Each dbms Interview Question Sets contains 12 questions.

1)   What is database?


2)   What is DBMS?


3)   What are the advantages of DBMS?

Controlling Data Redundancy
Sharing of Data
Data Consistency
Integration of Data
Integration Constraints
Data Security
Report Writers
Backup and Recovery Procedures

4)   What are the disadvantage in File Processing System?

The file processing system has the following major disadvantages:
Data redundancy and inconsistency.
Integrity Problems.
Security Problems.
Difficulty in accessing data.
Data isolation.

5)   Define the "integrity rules" in DBMS?

There are two Integrity rules.

6)   What is primary, candidate and foreign keys in DBMS?

Primary Key: The attribute or combination of attributes that uniquely identifies a row or record in a relation is known as primary key.
Candidate Key or Alternate key: A relation can have only one primary key. It may contain many fields or combination of fields that can be used as primary key. One field or combination of fields is used as primary key. The fields or combination of fields that are not used as primary key are known as candidate key or alternate key.
Foreign Key:A foreign key is an attribute or combination of attribute in a relation whose value match a primary key in another relation. The table in which foreign key is created is called as dependent table. The table to which foreign key is refers is known as parent table.

7)   What is a super key?

A superkey is a combination of attributes that can be uniquely used to identify a database record. A table might have many superkeys. Candidate keys are a special subset of superkeys that do not have any extraneous information in them.

8)   What is the difference between primary key and unique constraints?

1.Primary Key constraints are not nullable. UNIQUE constraints may be nullable.
2.When you create a UNIQUE constraint, the database automatically creates a UNIQUE index. For MS SQL Server databases, a PRIMARY KEY will generate a unique CLUSTERED INDEX.

9)   What is extension and intension in DBMS?


10)   What is a view? How it is related to data independence in DBMS?

In a database management system, a view is a way of portraying information in the database. Often thought of as a virtual table, the view doesn't actually store information itself, but just pulls it out of one or more existing tables.

11)   What is Data Model in DBMS?


12)   What is E-R model in DBMS?

