COMPTIA DATASYS+ DS0-001
CERTIFICATION EXAM WITH QUESTIONS
AND VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. Which database characteristic most directly describes atomicity
in an ACID-compliant transaction?
A. All operations in the transaction are treated as one indivisible unit
B. Committed data remains available after a server restart
C. Concurrent transactions are prevented from reading any data
D. Database indexes are automatically rebuilt after every transaction
Answer: A. All operations in the transaction are treated as one
indivisible unit
Rationale: Atomicity means a transaction either completes entirely or
none of its changes are committed. If a transaction contains five
operations and the fourth fails, the database rolls back the preceding
changes rather than leaving a partially completed transaction.
Durability concerns persistence after commit, consistency concerns
valid database states, and isolation concerns interactions among
concurrent transactions.
2. A database administrator executes the following transaction:
BEGIN TRANSACTION;
UPDATE Accounts
SET Balance = Balance - 500
1
,WHERE AccountID = 101;
UPDATE Accounts
SET Balance = Balance + 500
WHERE AccountID = 202;
COMMIT;
What is the primary purpose of COMMIT?
A. Remove all indexes from the Accounts table
B. Permanently make the transaction's changes part of the database state
C. Automatically encrypt the updated records
D. Release the database schema definition
Answer: B. Permanently make the transaction's changes part of the
database state
Rationale: COMMIT successfully completes a transaction and makes
its modifications persistent according to the database management
system's transaction semantics. Without a commit, the changes may
remain uncommitted and can potentially be rolled back.
3. Which SQL statement is specifically used to retrieve rows from a
relational database?
A. INSERT
B. UPDATE
C. SELECT
D. ALTER
Answer: C. SELECT
2
,Rationale: SELECT retrieves data from one or more tables or other
queryable database objects. INSERT adds rows, UPDATE modifies
existing rows, and ALTER changes database-object definitions such as
table structure.
4. An administrator needs to retrieve every employee whose salary
exceeds $80,000. Which query is most appropriate?
A. SELECT * FROM Employees WHERE Salary > 80000;
B. SELECT * FROM Employees HAVING Salary > 80000;
C. SELECT Employees WHERE Salary > 80000;
D. GET * FROM Employees IF Salary > 80000;
Answer: A. SELECT * FROM Employees WHERE Salary > 80000;
Rationale: The WHERE clause filters individual rows before grouping
or aggregation occurs. HAVING is primarily used to filter grouped
results, while GET and the syntax in option C are not valid standard
SQL forms for this operation.
5. Which database object is primarily designed to improve the speed
of data retrieval?
A. Trigger
B. Index
C. Stored procedure
D. Constraint
Answer: B. Index
Rationale: An index provides a data structure that allows the database
engine to locate qualifying rows more efficiently than scanning every
row in a table. Indexes can significantly improve read performance but
3
, consume storage and may add overhead to INSERT, UPDATE, and
DELETE operations.
6. A table contains CustomerID, CustomerName, Email, and
OrderTotal. The CustomerID uniquely identifies every customer.
Which column is the most appropriate primary key?
A. CustomerName
B. Email
C. OrderTotal
D. CustomerID
Answer: D. CustomerID
Rationale: A primary key should uniquely identify each row and
should be stable enough to serve as the row's identity. A customer
name may not be unique, email addresses can change, and order totals
are obviously not unique identifiers.
7. Which situation is the strongest example of a foreign-key
relationship?
A. An Employee table contains a unique EmployeeID
B. An Orders table contains CustomerID referencing
Customers.CustomerID
C. A table contains an automatically generated timestamp
D. A database contains two independent indexes
Answer: B. An Orders table contains CustomerID referencing
Customers.CustomerID
Rationale: A foreign key establishes a referential relationship between
a column in one table and a candidate or primary key in another table.
4
CERTIFICATION EXAM WITH QUESTIONS
AND VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. Which database characteristic most directly describes atomicity
in an ACID-compliant transaction?
A. All operations in the transaction are treated as one indivisible unit
B. Committed data remains available after a server restart
C. Concurrent transactions are prevented from reading any data
D. Database indexes are automatically rebuilt after every transaction
Answer: A. All operations in the transaction are treated as one
indivisible unit
Rationale: Atomicity means a transaction either completes entirely or
none of its changes are committed. If a transaction contains five
operations and the fourth fails, the database rolls back the preceding
changes rather than leaving a partially completed transaction.
Durability concerns persistence after commit, consistency concerns
valid database states, and isolation concerns interactions among
concurrent transactions.
2. A database administrator executes the following transaction:
BEGIN TRANSACTION;
UPDATE Accounts
SET Balance = Balance - 500
1
,WHERE AccountID = 101;
UPDATE Accounts
SET Balance = Balance + 500
WHERE AccountID = 202;
COMMIT;
What is the primary purpose of COMMIT?
A. Remove all indexes from the Accounts table
B. Permanently make the transaction's changes part of the database state
C. Automatically encrypt the updated records
D. Release the database schema definition
Answer: B. Permanently make the transaction's changes part of the
database state
Rationale: COMMIT successfully completes a transaction and makes
its modifications persistent according to the database management
system's transaction semantics. Without a commit, the changes may
remain uncommitted and can potentially be rolled back.
3. Which SQL statement is specifically used to retrieve rows from a
relational database?
A. INSERT
B. UPDATE
C. SELECT
D. ALTER
Answer: C. SELECT
2
,Rationale: SELECT retrieves data from one or more tables or other
queryable database objects. INSERT adds rows, UPDATE modifies
existing rows, and ALTER changes database-object definitions such as
table structure.
4. An administrator needs to retrieve every employee whose salary
exceeds $80,000. Which query is most appropriate?
A. SELECT * FROM Employees WHERE Salary > 80000;
B. SELECT * FROM Employees HAVING Salary > 80000;
C. SELECT Employees WHERE Salary > 80000;
D. GET * FROM Employees IF Salary > 80000;
Answer: A. SELECT * FROM Employees WHERE Salary > 80000;
Rationale: The WHERE clause filters individual rows before grouping
or aggregation occurs. HAVING is primarily used to filter grouped
results, while GET and the syntax in option C are not valid standard
SQL forms for this operation.
5. Which database object is primarily designed to improve the speed
of data retrieval?
A. Trigger
B. Index
C. Stored procedure
D. Constraint
Answer: B. Index
Rationale: An index provides a data structure that allows the database
engine to locate qualifying rows more efficiently than scanning every
row in a table. Indexes can significantly improve read performance but
3
, consume storage and may add overhead to INSERT, UPDATE, and
DELETE operations.
6. A table contains CustomerID, CustomerName, Email, and
OrderTotal. The CustomerID uniquely identifies every customer.
Which column is the most appropriate primary key?
A. CustomerName
B. Email
C. OrderTotal
D. CustomerID
Answer: D. CustomerID
Rationale: A primary key should uniquely identify each row and
should be stable enough to serve as the row's identity. A customer
name may not be unique, email addresses can change, and order totals
are obviously not unique identifiers.
7. Which situation is the strongest example of a foreign-key
relationship?
A. An Employee table contains a unique EmployeeID
B. An Orders table contains CustomerID referencing
Customers.CustomerID
C. A table contains an automatically generated timestamp
D. A database contains two independent indexes
Answer: B. An Orders table contains CustomerID referencing
Customers.CustomerID
Rationale: A foreign key establishes a referential relationship between
a column in one table and a candidate or primary key in another table.
4
