Data and Analytics SQL and Database Fundamentals 2

Question 1

Which aggregate function returns the total number of rows in a result set?

Accepted Answer

COUNT()

Answer

SUM()

Answer

AVG()

Answer

MAX()

Question 2

What is a foreign key in a relational database?

Accepted Answer

A column that references the primary key of another table

Answer

A key used for encryption

Answer

An index on multiple columns

Answer

A key that stores NULL values

Question 3

What SQL statement is used to retrieve data from a database?

Accepted Answer

SELECT

Answer

INSERT

Answer

UPDATE

Answer

DELETE

Question 4

Which SQL window function assigns a unique rank to each row within a partition?

Accepted Answer

ROW_NUMBER()

Answer

SUM() OVER

Answer

LAG()

Answer

PARTITION BY

Question 5

What does a NULL value represent in a database?

Accepted Answer

An unknown or missing value

Answer

Zero

Answer

An empty string

Answer

A negative number

Question 6

What is a view in SQL?

Accepted Answer

A virtual table defined by a stored query

Answer

A physical copy of a table

Answer

A type of database index

Answer

A backup of the database