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 is used for large analytical queries; OLAP handles day-to-day transactions

Answer

OLTP and OLAP are two names for the same type of database system

Answer

OLTP is used in data warehouses; OLAP is used in banking systems

Question 2

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

Accepted Answer

ALTER TABLE

Answer

SELECT

Answer

INSERT

Answer

UPDATE

Question 3

What is denormalization in databases?

Accepted Answer

Intentionally introducing redundancy to improve read performance

Answer

The process of converting a database to the first normal form

Answer

Removing all foreign keys from a table

Answer

Splitting a large table into smaller normalized tables

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 key that is encrypted using multiple algorithms

Answer

A foreign key that references more than one table

Answer

A key shared between two databases

Question 5

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

Accepted Answer

A relationship between entities

Answer

An entity

Answer

An attribute

Answer

A primary key attribute

Question 6

Which isolation level prevents dirty reads but allows non-repeatable reads?

Accepted Answer

Read Committed

Answer

Serializable

Answer

Repeatable Read

Answer

Read Uncommitted

Question 7

What is the purpose of a stored procedure in a database?

Accepted Answer

To precompile and store a set of SQL statements that can be executed repeatedly

Answer

To store backup copies of table data

Answer

To define the structure of a new table

Answer

To create an index on a frequently queried column