WGU D094 Objective Assessment Study Guide,
Comprehensive Exam Preparation Notes, Practice Questions,
and Concept Review for Western Governors University D094
Course Success and Assessment Mastery
Question 1: Which SQL command is used to remove a table and all its data from the database
permanently?
A. DELETE
B. DROP
C. TRUNCATE
D. REMOVE
CORRECT ANSWER: B. DROP
Rationale: The DROP command removes the table structure and all data permanently from the
database, whereas DELETE removes rows and TRUNCATE removes data but keeps the structure.
Question 2: In data governance, what is the primary purpose of a data dictionary?
A. To store backup copies of data
B. To define and document data elements and their meanings
C. To encrypt sensitive data fields
D. To manage user access permissions
CORRECT ANSWER: B. To define and document data elements and their meanings
Rationale: A data dictionary provides metadata about data elements, ensuring consistent
understanding and usage across the organization.
Question 3: Which normal form eliminates transitive dependencies?
A. First Normal Form (1NF)
B. Second Normal Form (2NF)
C. Third Normal Form (3NF)
D. Boyce-Codd Normal Form (BCNF)
CORRECT ANSWER: C. Third Normal Form (3NF)
Rationale: 3NF requires that the table is in 2NF and all non-key attributes are not transitively
dependent on the primary key.
Question 4: What does ACID stand for in the context of database transactions?
,A. Accuracy, Consistency, Isolation, Durability
B. Atomicity, Consistency, Isolation, Durability
C. Atomicity, Concurrency, Integrity, Durability
D. Accuracy, Concurrency, Isolation, Dependency
CORRECT ANSWER: B. Atomicity, Consistency, Isolation, Durability
Rationale: ACID properties ensure reliable processing of database transactions, guaranteeing
data validity despite errors or power failures.
Question 5: Which type of key uniquely identifies a record in a table?
A. Foreign Key
B. Secondary Key
C. Primary Key
D. Composite Key
CORRECT ANSWER: C. Primary Key
Rationale: A Primary Key uniquely identifies each record in a table and cannot contain NULL
values.
Question 6: In an Entity-Relationship Diagram (ERD), what does a crow's foot symbol indicate?
A. One-to-One relationship
B. One-to-Many relationship
C. Many-to-Many relationship
D. Optional relationship
CORRECT ANSWER: B. One-to-Many relationship
Rationale: The crow's foot notation represents the "many" side of a one-to-many relationship
between entities.
Question 7: Which SQL clause is used to filter groups after aggregation?
A. WHERE
B. ORDER BY
C. HAVING
D. GROUP BY
,CORRECT ANSWER: C. HAVING
Rationale: The HAVING clause filters results after the GROUP BY aggregation, whereas WHERE
filters rows before aggregation.
Question 8: What is the main advantage of using a NoSQL database over a relational database?
A. Strict schema enforcement
B. Horizontal scalability and flexibility
C. Complex join operations
D. ACID compliance by default
CORRECT ANSWER: B. Horizontal scalability and flexibility
Rationale: NoSQL databases are designed for horizontal scaling and handle unstructured or
semi-structured data more flexibly than relational databases.
Question 9: Which data type is most appropriate for storing a person's date of birth?
A. VARCHAR
B. INTEGER
C. DATE
D. TIMESTAMP
CORRECT ANSWER: C. DATE
Rationale: The DATE data type is specifically designed to store calendar dates without time
components, suitable for birth dates.
Question 10: What is the purpose of an index in a database?
A. To enforce data integrity
B. To speed up data retrieval operations
C. To backup data automatically
D. To encrypt stored data
CORRECT ANSWER: B. To speed up data retrieval operations
Rationale: Indexes create a data structure that improves the speed of data retrieval queries at
the cost of additional storage and write overhead.
Question 11: Which SQL statement is used to modify existing records in a table?
, A. INSERT
B. UPDATE
C. ALTER
D. MODIFY
CORRECT ANSWER: B. UPDATE
Rationale: The UPDATE statement is used to modify existing data in a table, whereas ALTER
changes the table structure.
Question 12: In data ethics, what does "informed consent" refer to?
A. Users agreeing to terms without reading
B. Users understanding how their data will be used before agreeing
C. Companies consenting to use data internally
D. Government consent for data collection
CORRECT ANSWER: B. Users understanding how their data will be used before agreeing
Rationale: Informed consent ensures individuals are fully aware of data usage purposes before
granting permission.
Question 13: Which join returns all records when there is a match in either left or right table?
A. INNER JOIN
B. LEFT JOIN
C. RIGHT JOIN
D. FULL OUTER JOIN
CORRECT ANSWER: D. FULL OUTER JOIN
Rationale: A FULL OUTER JOIN returns all records from both tables, with NULLs where no match
exists.
Question 14: What is a foreign key constraint used for?
A. To uniquely identify rows
B. To link two tables together based on a primary key
C. To encrypt data between tables
D. To index a column for speed
Comprehensive Exam Preparation Notes, Practice Questions,
and Concept Review for Western Governors University D094
Course Success and Assessment Mastery
Question 1: Which SQL command is used to remove a table and all its data from the database
permanently?
A. DELETE
B. DROP
C. TRUNCATE
D. REMOVE
CORRECT ANSWER: B. DROP
Rationale: The DROP command removes the table structure and all data permanently from the
database, whereas DELETE removes rows and TRUNCATE removes data but keeps the structure.
Question 2: In data governance, what is the primary purpose of a data dictionary?
A. To store backup copies of data
B. To define and document data elements and their meanings
C. To encrypt sensitive data fields
D. To manage user access permissions
CORRECT ANSWER: B. To define and document data elements and their meanings
Rationale: A data dictionary provides metadata about data elements, ensuring consistent
understanding and usage across the organization.
Question 3: Which normal form eliminates transitive dependencies?
A. First Normal Form (1NF)
B. Second Normal Form (2NF)
C. Third Normal Form (3NF)
D. Boyce-Codd Normal Form (BCNF)
CORRECT ANSWER: C. Third Normal Form (3NF)
Rationale: 3NF requires that the table is in 2NF and all non-key attributes are not transitively
dependent on the primary key.
Question 4: What does ACID stand for in the context of database transactions?
,A. Accuracy, Consistency, Isolation, Durability
B. Atomicity, Consistency, Isolation, Durability
C. Atomicity, Concurrency, Integrity, Durability
D. Accuracy, Concurrency, Isolation, Dependency
CORRECT ANSWER: B. Atomicity, Consistency, Isolation, Durability
Rationale: ACID properties ensure reliable processing of database transactions, guaranteeing
data validity despite errors or power failures.
Question 5: Which type of key uniquely identifies a record in a table?
A. Foreign Key
B. Secondary Key
C. Primary Key
D. Composite Key
CORRECT ANSWER: C. Primary Key
Rationale: A Primary Key uniquely identifies each record in a table and cannot contain NULL
values.
Question 6: In an Entity-Relationship Diagram (ERD), what does a crow's foot symbol indicate?
A. One-to-One relationship
B. One-to-Many relationship
C. Many-to-Many relationship
D. Optional relationship
CORRECT ANSWER: B. One-to-Many relationship
Rationale: The crow's foot notation represents the "many" side of a one-to-many relationship
between entities.
Question 7: Which SQL clause is used to filter groups after aggregation?
A. WHERE
B. ORDER BY
C. HAVING
D. GROUP BY
,CORRECT ANSWER: C. HAVING
Rationale: The HAVING clause filters results after the GROUP BY aggregation, whereas WHERE
filters rows before aggregation.
Question 8: What is the main advantage of using a NoSQL database over a relational database?
A. Strict schema enforcement
B. Horizontal scalability and flexibility
C. Complex join operations
D. ACID compliance by default
CORRECT ANSWER: B. Horizontal scalability and flexibility
Rationale: NoSQL databases are designed for horizontal scaling and handle unstructured or
semi-structured data more flexibly than relational databases.
Question 9: Which data type is most appropriate for storing a person's date of birth?
A. VARCHAR
B. INTEGER
C. DATE
D. TIMESTAMP
CORRECT ANSWER: C. DATE
Rationale: The DATE data type is specifically designed to store calendar dates without time
components, suitable for birth dates.
Question 10: What is the purpose of an index in a database?
A. To enforce data integrity
B. To speed up data retrieval operations
C. To backup data automatically
D. To encrypt stored data
CORRECT ANSWER: B. To speed up data retrieval operations
Rationale: Indexes create a data structure that improves the speed of data retrieval queries at
the cost of additional storage and write overhead.
Question 11: Which SQL statement is used to modify existing records in a table?
, A. INSERT
B. UPDATE
C. ALTER
D. MODIFY
CORRECT ANSWER: B. UPDATE
Rationale: The UPDATE statement is used to modify existing data in a table, whereas ALTER
changes the table structure.
Question 12: In data ethics, what does "informed consent" refer to?
A. Users agreeing to terms without reading
B. Users understanding how their data will be used before agreeing
C. Companies consenting to use data internally
D. Government consent for data collection
CORRECT ANSWER: B. Users understanding how their data will be used before agreeing
Rationale: Informed consent ensures individuals are fully aware of data usage purposes before
granting permission.
Question 13: Which join returns all records when there is a match in either left or right table?
A. INNER JOIN
B. LEFT JOIN
C. RIGHT JOIN
D. FULL OUTER JOIN
CORRECT ANSWER: D. FULL OUTER JOIN
Rationale: A FULL OUTER JOIN returns all records from both tables, with NULLs where no match
exists.
Question 14: What is a foreign key constraint used for?
A. To uniquely identify rows
B. To link two tables together based on a primary key
C. To encrypt data between tables
D. To index a column for speed
