WGU D426/C175 Data Management Foundations
WGU D426/C175 Data Management
Foundations OA Practice Exam Questions
and Answers 2026. Advanced NCLEX-Style
100 MCQs with Rationales
The D426/C175 OA heavily emphasizes database fundamentals, relational design, keys, ER
modeling, normalization (1NF–BCNF), SQL, joins, constraints, and database integrity.
Students consistently report that understanding concepts is more important than
memorization.
Q1
A database designer wants to ensure that each record in a table can be uniquely identified. Which
constraint should be implemented?
A. Foreign Key
B. Primary Key
C. Check Constraint
D. Default Constraint
Answer:
✅ B. Primary Key
Rationale:
A primary key uniquely identifies each row and cannot contain NULL values. Foreign keys
establish relationships between tables but do not guarantee uniqueness.
Q2
A table contains the following fields:
StudentID | StudentName | CourseID | CourseName
A student can enroll in multiple courses.
, WGU D426/C175 Data Management Foundations
What is the most likely issue with this design?
A. Referential integrity violation
B. Update anomaly
C. Missing index
D. Transaction conflict
Answer:
✅ B. Update Anomaly
Rationale:
Repeating CourseName across many records creates redundancy. If the course name changes,
multiple rows must be updated, creating an update anomaly.
Q3
Which SQL statement retrieves all columns from the Employee table?
A. GET * FROM Employee;
B. SELECT * FROM Employee;
C. RETRIEVE * Employee;
D. DISPLAY Employee.*;
Answer:
✅ B. SELECT * FROM Employee;
Rationale:
SELECT is the standard SQL command used to retrieve data from tables.
Q4
Which normal form eliminates repeating groups and ensures atomic values?
A. 1NF
B. 2NF
, WGU D426/C175 Data Management Foundations
C. 3NF
D. BCNF
Answer:
✅ A. 1NF
Rationale:
First Normal Form requires every attribute to contain a single, indivisible value.
Q5
A foreign key primarily serves which purpose?
A. Improve query speed
B. Enforce referential integrity
C. Eliminate duplicate rows
D. Encrypt data
Answer:
✅ B. Enforce Referential Integrity
Rationale:
Foreign keys ensure relationships remain valid between parent and child tables.
Q6
Which JOIN returns only matching rows from both tables?
A. LEFT JOIN
B. RIGHT JOIN
C. FULL JOIN
D. INNER JOIN
Answer:
✅ D. INNER JOIN
, WGU D426/C175 Data Management Foundations
Rationale:
INNER JOIN returns records where matching values exist in both tables.
Q7
What is the main purpose of normalization?
A. Increase redundancy
B. Reduce redundancy and anomalies
C. Improve security
D. Increase storage requirements
Answer:
✅ B. Reduce redundancy and anomalies
Rationale:
Normalization organizes data to minimize duplication and prevent insertion, update, and deletion
anomalies.
Q8
A table has a composite primary key consisting of OrderID and ProductID.
What does this indicate?
A. Each column is unique independently.
B. The combination of both columns must be unique.
C. Neither column can be indexed.
D. Both columns are foreign keys.
Answer:
✅ B. The combination of both columns must be unique.
Rationale:
Composite keys use multiple columns together to uniquely identify a record.
WGU D426/C175 Data Management
Foundations OA Practice Exam Questions
and Answers 2026. Advanced NCLEX-Style
100 MCQs with Rationales
The D426/C175 OA heavily emphasizes database fundamentals, relational design, keys, ER
modeling, normalization (1NF–BCNF), SQL, joins, constraints, and database integrity.
Students consistently report that understanding concepts is more important than
memorization.
Q1
A database designer wants to ensure that each record in a table can be uniquely identified. Which
constraint should be implemented?
A. Foreign Key
B. Primary Key
C. Check Constraint
D. Default Constraint
Answer:
✅ B. Primary Key
Rationale:
A primary key uniquely identifies each row and cannot contain NULL values. Foreign keys
establish relationships between tables but do not guarantee uniqueness.
Q2
A table contains the following fields:
StudentID | StudentName | CourseID | CourseName
A student can enroll in multiple courses.
, WGU D426/C175 Data Management Foundations
What is the most likely issue with this design?
A. Referential integrity violation
B. Update anomaly
C. Missing index
D. Transaction conflict
Answer:
✅ B. Update Anomaly
Rationale:
Repeating CourseName across many records creates redundancy. If the course name changes,
multiple rows must be updated, creating an update anomaly.
Q3
Which SQL statement retrieves all columns from the Employee table?
A. GET * FROM Employee;
B. SELECT * FROM Employee;
C. RETRIEVE * Employee;
D. DISPLAY Employee.*;
Answer:
✅ B. SELECT * FROM Employee;
Rationale:
SELECT is the standard SQL command used to retrieve data from tables.
Q4
Which normal form eliminates repeating groups and ensures atomic values?
A. 1NF
B. 2NF
, WGU D426/C175 Data Management Foundations
C. 3NF
D. BCNF
Answer:
✅ A. 1NF
Rationale:
First Normal Form requires every attribute to contain a single, indivisible value.
Q5
A foreign key primarily serves which purpose?
A. Improve query speed
B. Enforce referential integrity
C. Eliminate duplicate rows
D. Encrypt data
Answer:
✅ B. Enforce Referential Integrity
Rationale:
Foreign keys ensure relationships remain valid between parent and child tables.
Q6
Which JOIN returns only matching rows from both tables?
A. LEFT JOIN
B. RIGHT JOIN
C. FULL JOIN
D. INNER JOIN
Answer:
✅ D. INNER JOIN
, WGU D426/C175 Data Management Foundations
Rationale:
INNER JOIN returns records where matching values exist in both tables.
Q7
What is the main purpose of normalization?
A. Increase redundancy
B. Reduce redundancy and anomalies
C. Improve security
D. Increase storage requirements
Answer:
✅ B. Reduce redundancy and anomalies
Rationale:
Normalization organizes data to minimize duplication and prevent insertion, update, and deletion
anomalies.
Q8
A table has a composite primary key consisting of OrderID and ProductID.
What does this indicate?
A. Each column is unique independently.
B. The combination of both columns must be unique.
C. Neither column can be indexed.
D. Both columns are foreign keys.
Answer:
✅ B. The combination of both columns must be unique.
Rationale:
Composite keys use multiple columns together to uniquely identify a record.
