CPP Database Programming & SQL 3

Question 1

Which approach is the most effective way to prevent SQL injection attacks in application code?

Accepted Answer

Using parameterized queries (prepared statements)

Answer

Escaping all user input with a custom function

Answer

Validating that input contains no spaces

Answer

Encrypting the database connection string

Question 2

In the CAP theorem for distributed databases, which two properties can be simultaneously guaranteed during a network partition?

Accepted Answer

Consistency and Partition Tolerance, or Availability and Partition Tolerance — but not all three

Answer

Consistency and Availability

Answer

Availability and Durability

Answer

Consistency and Durability

Question 3

What is the key difference between DELETE and TRUNCATE in SQL?

Accepted Answer

DELETE can be rolled back and supports WHERE; TRUNCATE is typically faster and non-recoverable without a transaction

Answer

DELETE removes the table structure; TRUNCATE only removes rows

Answer

TRUNCATE is logged per row and supports WHERE; DELETE is not

Answer

There is no functional difference between DELETE and TRUNCATE

Question 4

Which normal form eliminates multi-valued dependencies, where one attribute independently determines two or more other attributes?

Accepted Answer

Fourth Normal Form (4NF)

Answer

Second Normal Form (2NF)

Answer

Third Normal Form (3NF)

Answer

Boyce-Codd Normal Form (BCNF)

Question 5

What does the SQL keyword DISTINCT do when used in a SELECT statement?

Accepted Answer

Removes duplicate rows from the query result

Answer

Sorts the result set in ascending order

Answer

Filters rows based on a condition

Answer

Limits the number of rows returned

Question 6

In a relational database, what does a composite key mean?

Accepted Answer

A primary key consisting of two or more columns combined to uniquely identify a row

Answer

A key derived from a formula or expression

Answer

A key that references multiple foreign tables simultaneously

Answer

An automatically generated surrogate key

Question 7

Which of the following best explains why using SELECT * in production queries is generally discouraged?

Accepted Answer

It retrieves all columns including unused ones, increasing network payload and breaking code if the schema changes

Answer

SELECT * is not valid standard SQL syntax

Answer

Databases do not support indexing on SELECT * queries

Answer

It automatically locks the table for writes during execution