WGU C170 DATABASE APPLICATIONS LABS PRACTICE QUESTIONS AND CORRECT ANSWERS WITH RATIONALES 2026
Q&A | STUDY GUIDE PDF
Core Domains
SQL Query Writing (SELECT, WHERE, JOINs)
Database Design & ER Modeling
Normalization (1NF, 2NF, 3NF)
Data Definition Language (CREATE, ALTER, DROP)
MySQL Workbench Operations
Table Constraints & Indexes
Aggregate Functions & Grouping
Subqueries & Advanced SELECT
Data Manipulation (INSERT, UPDATE, DELETE)
Professional Database Ethics & Best Practices
Introduction
This practice assessment is designed to help students prepare for the WGU C170 Database Applications Labs objective assessment. The exam covers
essential database management skills including SQL query writing, database design principles, normalization techniques, and MySQL Workbench
operations. This resource contains 100 multiple-choice questions that test both foundational theory and applied professional knowledge. Questions
include scenario-based problems requiring real-world decision-making, regulatory compliance understanding, and ethical considerations in database
administration. The multiple-choice format mirrors the actual assessment structure, emphasizing critical thinking and practical application of
database concepts. Success in this course prepares you for professional roles requiring data management competency.
Section One: Questions 1–100
,Question 1
Which SQL clause is used to filter rows before they are grouped in an aggregate query?
A. GROUP BY
B. ORDER BY
C. WHERE
D. HAVING
🟢C
🔴 RATIONALE: The WHERE clause filters rows before grouping occurs. HAVING filters after grouping, GROUP BY defines the grouping, and
ORDER BY sorts results.
Question 2
What is the primary purpose of normalization in database design?
A. Increase query speed
B. Reduce data redundancy and improve integrity
C. Add more tables to the database
D. Encrypt sensitive data
🟢B
🔴 RATIONALE: Normalization systematically reduces data redundancy and eliminates anomalies, thereby improving data integrity. Speed may
decrease initially due to more joins.
Question 3
In MySQL Workbench, which feature allows you to visually design database schemas?
A. SQL Editor
B. EER Diagrams
C. Data Export
D. Server Configuration
🟢B
🔴 RATIONALE: EER (Enhanced Entity-Relationship) Diagrams provide visual schema design capabilities in MySQL Workbench. SQL Editor is for
writing queries.
,Question 4
Which normal form requires that all non-key attributes be fully functionally dependent on the primary key?
A. 1NF
B. 2NF
C. 3NF
D. BCNF
🟢B
🔴 RATIONALE: 2NF requires that all non-key attributes be fully functionally dependent on the entire primary key, eliminating partial
dependencies. 1NF only requires atomic values.
Question 5
What SQL statement creates a new table?
A. INSERT TABLE
B. CREATE TABLE
C. NEW TABLE
D. ADD TABLE
🟢B
🔴 RATIONALE: CREATE TABLE is the standard SQL Data Definition Language (DDL) command for creating new tables.
Question 6
Which join returns only rows that have matching values in both tables?
A. LEFT JOIN
B. RIGHT JOIN
C. INNER JOIN
D. FULL JOIN
🟢C
🔴 RATIONALE: INNER JOIN returns only rows with matching values in both tables. LEFT/RIGHT JOINs include non-matching rows from one
table.
, Question 7
What does the SQL aggregate function COUNT(*) return?
A. Number of non-null values
B. Total number of rows including NULLs
C. Number of unique values
D. Sum of all values
🟢B
🔴 RATIONALE: COUNT(*) returns the total number of rows in a table, including rows with NULL values. COUNT(column) excludes NULLs.
Question 8
Which constraint ensures that a column cannot contain NULL values?
A. UNIQUE
B. PRIMARY KEY
C. NOT NULL
D. FOREIGN KEY
🟢C
🔴 RATIONALE: The NOT NULL constraint explicitly prevents NULL values in a column. PRIMARY KEY includes NOT NULL but also adds
uniqueness.
Question 9
In an ER diagram, what does a diamond shape represent?
A. Entity
B. Attribute
C. Relationship
D. Compound entity
🟢C
🔴 RATIONALE: Diamond shapes represent relationships between entities in ER diagrams. Rectangles represent entities, ellipses represent
attributes.
Q&A | STUDY GUIDE PDF
Core Domains
SQL Query Writing (SELECT, WHERE, JOINs)
Database Design & ER Modeling
Normalization (1NF, 2NF, 3NF)
Data Definition Language (CREATE, ALTER, DROP)
MySQL Workbench Operations
Table Constraints & Indexes
Aggregate Functions & Grouping
Subqueries & Advanced SELECT
Data Manipulation (INSERT, UPDATE, DELETE)
Professional Database Ethics & Best Practices
Introduction
This practice assessment is designed to help students prepare for the WGU C170 Database Applications Labs objective assessment. The exam covers
essential database management skills including SQL query writing, database design principles, normalization techniques, and MySQL Workbench
operations. This resource contains 100 multiple-choice questions that test both foundational theory and applied professional knowledge. Questions
include scenario-based problems requiring real-world decision-making, regulatory compliance understanding, and ethical considerations in database
administration. The multiple-choice format mirrors the actual assessment structure, emphasizing critical thinking and practical application of
database concepts. Success in this course prepares you for professional roles requiring data management competency.
Section One: Questions 1–100
,Question 1
Which SQL clause is used to filter rows before they are grouped in an aggregate query?
A. GROUP BY
B. ORDER BY
C. WHERE
D. HAVING
🟢C
🔴 RATIONALE: The WHERE clause filters rows before grouping occurs. HAVING filters after grouping, GROUP BY defines the grouping, and
ORDER BY sorts results.
Question 2
What is the primary purpose of normalization in database design?
A. Increase query speed
B. Reduce data redundancy and improve integrity
C. Add more tables to the database
D. Encrypt sensitive data
🟢B
🔴 RATIONALE: Normalization systematically reduces data redundancy and eliminates anomalies, thereby improving data integrity. Speed may
decrease initially due to more joins.
Question 3
In MySQL Workbench, which feature allows you to visually design database schemas?
A. SQL Editor
B. EER Diagrams
C. Data Export
D. Server Configuration
🟢B
🔴 RATIONALE: EER (Enhanced Entity-Relationship) Diagrams provide visual schema design capabilities in MySQL Workbench. SQL Editor is for
writing queries.
,Question 4
Which normal form requires that all non-key attributes be fully functionally dependent on the primary key?
A. 1NF
B. 2NF
C. 3NF
D. BCNF
🟢B
🔴 RATIONALE: 2NF requires that all non-key attributes be fully functionally dependent on the entire primary key, eliminating partial
dependencies. 1NF only requires atomic values.
Question 5
What SQL statement creates a new table?
A. INSERT TABLE
B. CREATE TABLE
C. NEW TABLE
D. ADD TABLE
🟢B
🔴 RATIONALE: CREATE TABLE is the standard SQL Data Definition Language (DDL) command for creating new tables.
Question 6
Which join returns only rows that have matching values in both tables?
A. LEFT JOIN
B. RIGHT JOIN
C. INNER JOIN
D. FULL JOIN
🟢C
🔴 RATIONALE: INNER JOIN returns only rows with matching values in both tables. LEFT/RIGHT JOINs include non-matching rows from one
table.
, Question 7
What does the SQL aggregate function COUNT(*) return?
A. Number of non-null values
B. Total number of rows including NULLs
C. Number of unique values
D. Sum of all values
🟢B
🔴 RATIONALE: COUNT(*) returns the total number of rows in a table, including rows with NULL values. COUNT(column) excludes NULLs.
Question 8
Which constraint ensures that a column cannot contain NULL values?
A. UNIQUE
B. PRIMARY KEY
C. NOT NULL
D. FOREIGN KEY
🟢C
🔴 RATIONALE: The NOT NULL constraint explicitly prevents NULL values in a column. PRIMARY KEY includes NOT NULL but also adds
uniqueness.
Question 9
In an ER diagram, what does a diamond shape represent?
A. Entity
B. Attribute
C. Relationship
D. Compound entity
🟢C
🔴 RATIONALE: Diamond shapes represent relationships between entities in ER diagrams. Rectangles represent entities, ellipses represent
attributes.
