1
CompTIA DataSys+ (DS0-001) Version 2.0:
Advanced Practice Examination Featuring
150 High-Fidelity Multiple-Choice Questions
Across All Five Domains with
Comprehensive Rationales for Certification
Mastery and Exam Readiness a well
detailed one written and
graded A+ upgraded
DOMAIN 1: DATABASE FUNDAMENTALS (36 Questions)
Question 1
Which of the following transaction isolation levels prevents dirty reads but allows non-
repeatable reads?
A. READ UNCOMMITTED
B. READ COMMITTED
, 2
C. REPEATABLE READ
D. SERIALIZABLE
-” detailed answer 100 % correct :-”B
Rationale: READ COMMITTED prevents dirty reads by not allowing reading uncommitted data,
but it does allow non-repeatable reads (different results within the same transaction).
REPEATABLE READ prevents non-repeatable reads, and SERIALIZABLE provides full isolation.
Question 2
A database uses a composite primary key consisting of two columns: OrderID and ProductID. If a
non-key attribute Quantity depends only on OrderID, this violates which normal form?
A. 1NF
B. 2NF
C. 3NF
D. BCNF
-” detailed answer 100 % correct :-”B
Rationale: This is a partial dependency (a non-key attribute depends on part of a composite
primary key), which violates Second Normal Form (2NF). 2NF requires full functional
dependency on the entire primary key.
Question 3
Which SQL data type is best suited for storing a fixed-length string of exactly 10 characters?
A. VARCHAR(10)
B. CHAR(10)
C. TEXT
D. BINARY(10)
-” detailed answer 100 % correct :-”B
Rationale: CHAR(n) stores fixed-length strings of exactly n characters, padding with spaces if
necessary. VARCHAR is variable-length, TEXT is for large strings, and BINARY is for binary data.
Question 4
, 3
In the context of NoSQL databases, which property is associated with the BASE model?
A. Atomicity
B. Consistency
C. Eventual consistency
D. Durability
-” detailed answer 100 % correct :-”C
Rationale: BASE stands for Basically Available, Soft state, Eventual consistency. Eventual
consistency is a key property where data will become consistent over time, unlike ACID's strong
consistency.
Question 5
A DBA needs to retrieve the total sales amount per product category. Which SQL clause must be
used?
A. WHERE
B. GROUP BY
C. HAVING
D. ORDER BY
-” detailed answer 100 % correct :-”B
Rationale: GROUP BY groups rows that have the same values in specified columns, allowing
aggregate functions like SUM to be applied per group.
Question 6
Which ACID property ensures that once a transaction is committed, it remains permanent even
in the event of a system failure?
A. Atomicity
B. Consistency
C. Isolation
D. Durability
-” detailed answer 100 % correct :-”D
, 4
Rationale: Durability guarantees that committed transactions are stored permanently and
survive system crashes, typically through transaction logs and write-ahead logging.
Question 7
A company needs to store data with complex relationships (e.g., social network connections).
Which type of database is most suitable?
A. Relational
B. Document
C. Graph
D. Key-value
-” detailed answer 100 % correct :-”C
Rationale: Graph databases are optimized for storing and querying complex relationships
between entities, making them ideal for social networks, recommendation engines, and fraud
detection.
Question 8
Which SQL command is used to permanently remove all data from a table but keep its structure
for future use?
A. DROP TABLE
B. DELETE FROM table
C. TRUNCATE TABLE
D. REMOVE TABLE
-” detailed answer 100 % correct :-”C
Rationale: TRUNCATE TABLE removes all rows but retains the table structure, indexes, and
constraints. It is faster than DELETE because it deallocates data pages with minimal logging.
Question 9
What is the primary difference between a view and a materialized view?
A. Views are updatable; materialized views are not
B. Views are virtual; materialized views store data physically
CompTIA DataSys+ (DS0-001) Version 2.0:
Advanced Practice Examination Featuring
150 High-Fidelity Multiple-Choice Questions
Across All Five Domains with
Comprehensive Rationales for Certification
Mastery and Exam Readiness a well
detailed one written and
graded A+ upgraded
DOMAIN 1: DATABASE FUNDAMENTALS (36 Questions)
Question 1
Which of the following transaction isolation levels prevents dirty reads but allows non-
repeatable reads?
A. READ UNCOMMITTED
B. READ COMMITTED
, 2
C. REPEATABLE READ
D. SERIALIZABLE
-” detailed answer 100 % correct :-”B
Rationale: READ COMMITTED prevents dirty reads by not allowing reading uncommitted data,
but it does allow non-repeatable reads (different results within the same transaction).
REPEATABLE READ prevents non-repeatable reads, and SERIALIZABLE provides full isolation.
Question 2
A database uses a composite primary key consisting of two columns: OrderID and ProductID. If a
non-key attribute Quantity depends only on OrderID, this violates which normal form?
A. 1NF
B. 2NF
C. 3NF
D. BCNF
-” detailed answer 100 % correct :-”B
Rationale: This is a partial dependency (a non-key attribute depends on part of a composite
primary key), which violates Second Normal Form (2NF). 2NF requires full functional
dependency on the entire primary key.
Question 3
Which SQL data type is best suited for storing a fixed-length string of exactly 10 characters?
A. VARCHAR(10)
B. CHAR(10)
C. TEXT
D. BINARY(10)
-” detailed answer 100 % correct :-”B
Rationale: CHAR(n) stores fixed-length strings of exactly n characters, padding with spaces if
necessary. VARCHAR is variable-length, TEXT is for large strings, and BINARY is for binary data.
Question 4
, 3
In the context of NoSQL databases, which property is associated with the BASE model?
A. Atomicity
B. Consistency
C. Eventual consistency
D. Durability
-” detailed answer 100 % correct :-”C
Rationale: BASE stands for Basically Available, Soft state, Eventual consistency. Eventual
consistency is a key property where data will become consistent over time, unlike ACID's strong
consistency.
Question 5
A DBA needs to retrieve the total sales amount per product category. Which SQL clause must be
used?
A. WHERE
B. GROUP BY
C. HAVING
D. ORDER BY
-” detailed answer 100 % correct :-”B
Rationale: GROUP BY groups rows that have the same values in specified columns, allowing
aggregate functions like SUM to be applied per group.
Question 6
Which ACID property ensures that once a transaction is committed, it remains permanent even
in the event of a system failure?
A. Atomicity
B. Consistency
C. Isolation
D. Durability
-” detailed answer 100 % correct :-”D
, 4
Rationale: Durability guarantees that committed transactions are stored permanently and
survive system crashes, typically through transaction logs and write-ahead logging.
Question 7
A company needs to store data with complex relationships (e.g., social network connections).
Which type of database is most suitable?
A. Relational
B. Document
C. Graph
D. Key-value
-” detailed answer 100 % correct :-”C
Rationale: Graph databases are optimized for storing and querying complex relationships
between entities, making them ideal for social networks, recommendation engines, and fraud
detection.
Question 8
Which SQL command is used to permanently remove all data from a table but keep its structure
for future use?
A. DROP TABLE
B. DELETE FROM table
C. TRUNCATE TABLE
D. REMOVE TABLE
-” detailed answer 100 % correct :-”C
Rationale: TRUNCATE TABLE removes all rows but retains the table structure, indexes, and
constraints. It is faster than DELETE because it deallocates data pages with minimal logging.
Question 9
What is the primary difference between a view and a materialized view?
A. Views are updatable; materialized views are not
B. Views are virtual; materialized views store data physically
