WGU D427 DATA MANAGEMENT
APPLICATIONS COMPREHENSIVE
PRACTICE EXAM QUESTIONS AND
ANSWERS
1. Which normal form is specifically designed to address anomalies resulting from multiple
multi-valued dependencies?
A. Third Normal Form (3NF)
B. Boyce-Codd Normal Form (BCNF)
C. Fourth Normal Form (4NF)
D. Second Normal Form (2NF)
Answer: C
Conceptual Explanation: Fourth Normal Form (4NF) is reached when a table is in BCNF
and has no multi-valued dependencies.
2. In a SQL statement, which clause is used to filter groups returned by an aggregate
function?
A. WHERE
,B. ORDER BY
C. HAVING
D. GROUP BY
Answer: C
Conceptual Explanation: The HAVING clause was added to SQL because the WHERE
keyword could not be used with aggregate functions.
3. Which of the following commands is used to remove all records from a table while keeping
the table structure intact, and cannot be rolled back in some database systems?
A. DELETE
B. DROP
C. REMOVE
D. TRUNCATE
Answer: D
Conceptual Explanation: TRUNCATE removes all rows from a table and is typically a DDL
operation, making it faster than DELETE but often non-transactional depending on the
DBMS.
4. What is the effect of the ‘ON DELETE CASCADE’ constraint in a foreign key definition?
A. It automatically deletes all related rows in the child table when a row in the parent table
is deleted.
, B. It sets the foreign key values in the child rows to NULL when the parent row is deleted.
C. It prevents the deletion of a parent row if child rows exist.
D. It prompts the user to delete child rows manually.
Answer: A
Conceptual Explanation: ON DELETE CASCADE ensures referential integrity by
automatically removing child records when the referenced parent record is deleted.
5. Which type of join returns all records from the left table and the matched records from the
right table, with NULLs in place for unmatched right-side rows?
A. INNER JOIN
B. RIGHT JOIN
C. LEFT JOIN
D. CROSS JOIN
Answer: C
Conceptual Explanation: A LEFT JOIN (or LEFT OUTER JOIN) returns all rows from the
left table and the matching rows from the right table; non-matching rows from the right
result in NULL.
6. What is the primary difference between a PRIMARY KEY and a UNIQUE constraint?
A. A table can have multiple PRIMARY KEYs but only one UNIQUE constraint.
APPLICATIONS COMPREHENSIVE
PRACTICE EXAM QUESTIONS AND
ANSWERS
1. Which normal form is specifically designed to address anomalies resulting from multiple
multi-valued dependencies?
A. Third Normal Form (3NF)
B. Boyce-Codd Normal Form (BCNF)
C. Fourth Normal Form (4NF)
D. Second Normal Form (2NF)
Answer: C
Conceptual Explanation: Fourth Normal Form (4NF) is reached when a table is in BCNF
and has no multi-valued dependencies.
2. In a SQL statement, which clause is used to filter groups returned by an aggregate
function?
A. WHERE
,B. ORDER BY
C. HAVING
D. GROUP BY
Answer: C
Conceptual Explanation: The HAVING clause was added to SQL because the WHERE
keyword could not be used with aggregate functions.
3. Which of the following commands is used to remove all records from a table while keeping
the table structure intact, and cannot be rolled back in some database systems?
A. DELETE
B. DROP
C. REMOVE
D. TRUNCATE
Answer: D
Conceptual Explanation: TRUNCATE removes all rows from a table and is typically a DDL
operation, making it faster than DELETE but often non-transactional depending on the
DBMS.
4. What is the effect of the ‘ON DELETE CASCADE’ constraint in a foreign key definition?
A. It automatically deletes all related rows in the child table when a row in the parent table
is deleted.
, B. It sets the foreign key values in the child rows to NULL when the parent row is deleted.
C. It prevents the deletion of a parent row if child rows exist.
D. It prompts the user to delete child rows manually.
Answer: A
Conceptual Explanation: ON DELETE CASCADE ensures referential integrity by
automatically removing child records when the referenced parent record is deleted.
5. Which type of join returns all records from the left table and the matched records from the
right table, with NULLs in place for unmatched right-side rows?
A. INNER JOIN
B. RIGHT JOIN
C. LEFT JOIN
D. CROSS JOIN
Answer: C
Conceptual Explanation: A LEFT JOIN (or LEFT OUTER JOIN) returns all rows from the
left table and the matching rows from the right table; non-matching rows from the right
result in NULL.
6. What is the primary difference between a PRIMARY KEY and a UNIQUE constraint?
A. A table can have multiple PRIMARY KEYs but only one UNIQUE constraint.
