Web Development Database Basics 5

Question 1

What is the difference between a clustered and a non-clustered index?

Accepted Answer

A clustered index sorts and stores data rows physically, while a non-clustered index is a separate structure

Answer

A clustered index determines the physical order of data in the table, while a non-clustered index is a separate lookup structure pointing to data rows.

Question 2

Which SQL set operation returns rows that appear in the first query but NOT in the second?

Accepted Answer

EXCEPT

Answer

EXCEPT (or MINUS in some databases) returns rows from the first SELECT that are not present in the second SELECT result.

Question 3

What is denormalization in database design?

Accepted Answer

Intentionally introducing redundancy to improve read performance

Answer

Denormalization adds redundant data to a database to reduce complex joins and speed up read queries, at the cost of more storage and harder updates.

Question 4

What does ORM stand for in web development?

Accepted Answer

Object Relational Mapping

Answer

ORM (Object Relational Mapping) is a technique that lets you interact with a relational database using object-oriented code instead of raw SQL.

Question 5

Which SQL function would you use to return the current date and time?

Accepted Answer

NOW()

Answer

NOW() returns the current date and time in most SQL databases, though some databases use GETDATE() or CURRENT_TIMESTAMP.

Web Development Practice Test

Web Development Practice Test

Web Development Database Basics 5