WGU D426 Objective Assessment Final
Exam 2025/2026 | Actual Exam | Western
Governors University | Data Management
Applications
1. Which of the following is a primary key constraint in a relational database?
A. Ensures no duplicate values in a column
B. Allows NULL values in a column
C. Links two tables together
D. Defines the data type of a column
Answer: A
Solution: A primary key uniquely identifies each record in a table and does not allow duplicates
or NULL values.
2. What is the main purpose of database normalization?
A. Improve query performance by adding indexes
B. Reduce redundancy and improve data integrity
C. Make tables larger for more data
D. Convert SQL to NoSQL
Answer: B
Solution: Normalization organizes data into tables to minimize redundancy and maintain
consistency.
3. Which SQL statement is used to remove a table and all its data?
A. DELETE TABLE table_name;
B. DROP TABLE table_name;
C. REMOVE TABLE table_name;
D. TRUNCATE TABLE table_name;
Answer: B
Solution: DROP TABLE deletes the table structure and its data permanently.
,4. Which SQL clause is used to filter records returned by a query?
A. GROUP BY
B. WHERE
C. ORDER BY
D. HAVING
Answer: B
Solution: The WHERE clause filters rows based on a specified condition.
5. What type of relationship exists when one record in a table relates to many records in
another table?
A. One-to-One
B. One-to-Many
C. Many-to-Many
D. Self-Referencing
Answer: B
Solution: One-to-Many relationships are common in relational databases, e.g., a customer can
have many orders.
6. In SQL, which function is used to count the number of rows in a table?
A. SUM()
B. COUNT()
C. AVG()
D. ROWS()
Answer: B
Solution: COUNT() returns the total number of rows matching a condition.
7. Which of the following is an example of a NoSQL database?
A. MySQL
B. PostgreSQL
C. MongoDB
D. Oracle
Answer: C
Solution: MongoDB is a document-oriented NoSQL database.
,8. What is a foreign key?
A. A key that uniquely identifies a table
B. A key that links one table to another table
C. A key that stores encrypted data
D. A key used for sorting data
Answer: B
Solution: A foreign key creates a relationship between two tables by referencing the primary
key of another table.
9. Which SQL command is used to add a new record to a table?
A. INSERT INTO
B. UPDATE
C. ADD RECORD
D. CREATE RECORD
Answer: A
Solution: INSERT INTO adds new rows to a table.
10. Which type of index improves search performance but may slow down insert/update
operations?
A. Clustered index
B. Non-clustered index
C. Foreign index
D. Primary index
Answer: B
Solution: Non-clustered indexes speed up queries but add overhead during data modification.
11. Which SQL keyword is used to sort the result set?
A. SORT BY
B. ORDER BY
C. GROUP BY
D. FILTER BY
Answer: B
Solution: ORDER BY sorts query results ascending (ASC) or descending (DESC).
, 12. Which of the following ensures that a column cannot contain NULL values?
A. PRIMARY KEY
B. NOT NULL
C. UNIQUE
D. FOREIGN KEY
Answer: B
Solution: NOT NULL constraint enforces that a column must have a value.
13. What does ACID stand for in database systems?
A. Atomicity, Consistency, Isolation, Durability
B. Accuracy, Consistency, Integrity, Data
C. Atomicity, Coordination, Isolation, Data
D. Access, Control, Indexing, Durability
Answer: A
Solution: ACID properties ensure reliable database transactions.
14. In relational databases, a table column that can store multiple values in a single cell
violates which normal form?
A. First Normal Form (1NF)
B. Second Normal Form (2NF)
C. Third Normal Form (3NF)
D. Fourth Normal Form (4NF)
Answer: A
Solution: 1NF requires that each column contains atomic (single) values.
15. Which of the following is NOT a valid SQL aggregate function?
A. SUM()
B. AVG()
C. CONCAT()
D. MIN()
Answer: C
Solution: CONCAT() is a string function, not an aggregate function.
Exam 2025/2026 | Actual Exam | Western
Governors University | Data Management
Applications
1. Which of the following is a primary key constraint in a relational database?
A. Ensures no duplicate values in a column
B. Allows NULL values in a column
C. Links two tables together
D. Defines the data type of a column
Answer: A
Solution: A primary key uniquely identifies each record in a table and does not allow duplicates
or NULL values.
2. What is the main purpose of database normalization?
A. Improve query performance by adding indexes
B. Reduce redundancy and improve data integrity
C. Make tables larger for more data
D. Convert SQL to NoSQL
Answer: B
Solution: Normalization organizes data into tables to minimize redundancy and maintain
consistency.
3. Which SQL statement is used to remove a table and all its data?
A. DELETE TABLE table_name;
B. DROP TABLE table_name;
C. REMOVE TABLE table_name;
D. TRUNCATE TABLE table_name;
Answer: B
Solution: DROP TABLE deletes the table structure and its data permanently.
,4. Which SQL clause is used to filter records returned by a query?
A. GROUP BY
B. WHERE
C. ORDER BY
D. HAVING
Answer: B
Solution: The WHERE clause filters rows based on a specified condition.
5. What type of relationship exists when one record in a table relates to many records in
another table?
A. One-to-One
B. One-to-Many
C. Many-to-Many
D. Self-Referencing
Answer: B
Solution: One-to-Many relationships are common in relational databases, e.g., a customer can
have many orders.
6. In SQL, which function is used to count the number of rows in a table?
A. SUM()
B. COUNT()
C. AVG()
D. ROWS()
Answer: B
Solution: COUNT() returns the total number of rows matching a condition.
7. Which of the following is an example of a NoSQL database?
A. MySQL
B. PostgreSQL
C. MongoDB
D. Oracle
Answer: C
Solution: MongoDB is a document-oriented NoSQL database.
,8. What is a foreign key?
A. A key that uniquely identifies a table
B. A key that links one table to another table
C. A key that stores encrypted data
D. A key used for sorting data
Answer: B
Solution: A foreign key creates a relationship between two tables by referencing the primary
key of another table.
9. Which SQL command is used to add a new record to a table?
A. INSERT INTO
B. UPDATE
C. ADD RECORD
D. CREATE RECORD
Answer: A
Solution: INSERT INTO adds new rows to a table.
10. Which type of index improves search performance but may slow down insert/update
operations?
A. Clustered index
B. Non-clustered index
C. Foreign index
D. Primary index
Answer: B
Solution: Non-clustered indexes speed up queries but add overhead during data modification.
11. Which SQL keyword is used to sort the result set?
A. SORT BY
B. ORDER BY
C. GROUP BY
D. FILTER BY
Answer: B
Solution: ORDER BY sorts query results ascending (ASC) or descending (DESC).
, 12. Which of the following ensures that a column cannot contain NULL values?
A. PRIMARY KEY
B. NOT NULL
C. UNIQUE
D. FOREIGN KEY
Answer: B
Solution: NOT NULL constraint enforces that a column must have a value.
13. What does ACID stand for in database systems?
A. Atomicity, Consistency, Isolation, Durability
B. Accuracy, Consistency, Integrity, Data
C. Atomicity, Coordination, Isolation, Data
D. Access, Control, Indexing, Durability
Answer: A
Solution: ACID properties ensure reliable database transactions.
14. In relational databases, a table column that can store multiple values in a single cell
violates which normal form?
A. First Normal Form (1NF)
B. Second Normal Form (2NF)
C. Third Normal Form (3NF)
D. Fourth Normal Form (4NF)
Answer: A
Solution: 1NF requires that each column contains atomic (single) values.
15. Which of the following is NOT a valid SQL aggregate function?
A. SUM()
B. AVG()
C. CONCAT()
D. MIN()
Answer: C
Solution: CONCAT() is a string function, not an aggregate function.
