Cognizant Database Management Systems 3

Question 1

What is the difference between OLTP and OLAP systems?

Accepted Answer

OLTP handles day-to-day transactional operations; OLAP is used for complex analytical queries on historical data

Answer

OLTP (Online Transaction Processing) is optimized for fast, simple read/write transactions, while OLAP (Online Analytical Processing) is optimized for complex queries over large historical datasets.

Question 2

Which of the following is an example of a DDL (Data Definition Language) command?

Accepted Answer

ALTER TABLE

Answer

ALTER TABLE is a DDL command that modifies the structure of an existing table, while SELECT, INSERT, and UPDATE are DML commands.

Question 3

What is denormalization in databases?

Accepted Answer

Intentionally introducing redundancy to improve read performance

Answer

Denormalization intentionally adds redundancy to a normalized database to reduce complex joins and improve read query performance.

Question 4

What is a composite key in a relational database?

Accepted Answer

A primary key made up of two or more columns to uniquely identify a record

Answer

A composite key uses two or more columns together as the primary key to uniquely identify a row when no single column is sufficient.

Question 5

In an ER diagram, what does a diamond shape typically represent?

Accepted Answer

A relationship between entities

Answer

In an Entity-Relationship (ER) diagram, diamonds represent relationships between entities, rectangles represent entities, and ovals represent attributes.

(Cognizant) Cognizant Test Practice Test

(Cognizant) Cognizant Test Practice Test

Cognizant Database Management Systems 3