WGU D427 — DATA MANAGEMENT: APPLICATIONS
ENHANCED OBJECTIVE ASSESSMENT STUDY GUIDE
2026 EDITION • ORIGINAL PRACTICE QUESTIONS • ANSWERS & RATIONALES
Source note: The supplied Stuvia page was used only to identify the subject, broad study style, and publicly visible topic
emphasis. This guide does not reproduce or claim access to locked/premium text or actual assessment questions. All practice
content below is newly written.
Purpose: Build exam readiness through repeated exposure to SQL syntax, relational reasoning, normalization, joins, constraints,
transactions, views, indexes, and scenario-based troubleshooting.
Study method: Answer first, then check the model answer and rationale. For SQL-related items, type the statement yourself. For design
questions, identify the grain and functional dependencies before choosing an answer.
WGU D427 Enhanced Study Guide | Original Practice Material Page 1
, CONTENTS
1. SQL Fundamentals & Query Execution
2. Aggregate Functions, GROUP BY & HAVING
3. Joins & Multi-Table Queries
4. Subqueries, IN, EXISTS & Set Operations
5. Data Types, DDL & Table Design
6. Keys, Constraints & Referential Integrity
7. DML, Transactions & ACID
8. Normalization & Database Design
9. Views, Indexes & Query Performance
10. Integrated Exam Scenarios
11. Rapid Review & Exam Traps
12. Final Mixed Mock Assessment
13. Exam-Day Checklist
WGU D427 Enhanced Study Guide | Original Practice Material Page 2
, 1. SQL Fundamentals & Query Execution
Exam Focus: WHERE vs HAVING, NULL, LIKE, DISTINCT, LIMIT, ORDER BY and clause order.
Question 1
Which clause filters rows before grouping?
Correct Answer: B. WHERE
Rationale: WHERE filters individual rows before GROUP BY and aggregation.
Question 2
What is the default ORDER BY direction?
Correct Answer: B. ASC
Rationale: Ascending order is the default when ASC or DESC is omitted.
Question 3
Which LIKE pattern finds names beginning with 'Sm'?
Correct Answer: B. 'Sm%'
Rationale: Percent matches zero or more characters after Sm.
Question 4
Which LIKE wildcard matches exactly one character?
Correct Answer: C. '_'
Rationale: Underscore matches exactly one character.
Question 5
Which function counts every row, including rows with NULL in other columns?
Correct Answer: B. COUNT(*)
Rationale: COUNT(*) counts rows; COUNT(column) ignores NULL expression values.
Question 6
How should NULL be tested?
Correct Answer: C. IS NULL
Rationale: NULL represents an unknown/missing value and is not tested with = NULL.
Question 7
What removes duplicate result rows?
Correct Answer: B. DISTINCT
Rationale: SELECT DISTINCT removes duplicate selected-row combinations.
Question 8
Which operator tests an inclusive range?
Correct Answer: A. BETWEEN
Rationale: BETWEEN includes both endpoints.
WGU D427 Enhanced Study Guide | Original Practice Material Page 3
ENHANCED OBJECTIVE ASSESSMENT STUDY GUIDE
2026 EDITION • ORIGINAL PRACTICE QUESTIONS • ANSWERS & RATIONALES
Source note: The supplied Stuvia page was used only to identify the subject, broad study style, and publicly visible topic
emphasis. This guide does not reproduce or claim access to locked/premium text or actual assessment questions. All practice
content below is newly written.
Purpose: Build exam readiness through repeated exposure to SQL syntax, relational reasoning, normalization, joins, constraints,
transactions, views, indexes, and scenario-based troubleshooting.
Study method: Answer first, then check the model answer and rationale. For SQL-related items, type the statement yourself. For design
questions, identify the grain and functional dependencies before choosing an answer.
WGU D427 Enhanced Study Guide | Original Practice Material Page 1
, CONTENTS
1. SQL Fundamentals & Query Execution
2. Aggregate Functions, GROUP BY & HAVING
3. Joins & Multi-Table Queries
4. Subqueries, IN, EXISTS & Set Operations
5. Data Types, DDL & Table Design
6. Keys, Constraints & Referential Integrity
7. DML, Transactions & ACID
8. Normalization & Database Design
9. Views, Indexes & Query Performance
10. Integrated Exam Scenarios
11. Rapid Review & Exam Traps
12. Final Mixed Mock Assessment
13. Exam-Day Checklist
WGU D427 Enhanced Study Guide | Original Practice Material Page 2
, 1. SQL Fundamentals & Query Execution
Exam Focus: WHERE vs HAVING, NULL, LIKE, DISTINCT, LIMIT, ORDER BY and clause order.
Question 1
Which clause filters rows before grouping?
Correct Answer: B. WHERE
Rationale: WHERE filters individual rows before GROUP BY and aggregation.
Question 2
What is the default ORDER BY direction?
Correct Answer: B. ASC
Rationale: Ascending order is the default when ASC or DESC is omitted.
Question 3
Which LIKE pattern finds names beginning with 'Sm'?
Correct Answer: B. 'Sm%'
Rationale: Percent matches zero or more characters after Sm.
Question 4
Which LIKE wildcard matches exactly one character?
Correct Answer: C. '_'
Rationale: Underscore matches exactly one character.
Question 5
Which function counts every row, including rows with NULL in other columns?
Correct Answer: B. COUNT(*)
Rationale: COUNT(*) counts rows; COUNT(column) ignores NULL expression values.
Question 6
How should NULL be tested?
Correct Answer: C. IS NULL
Rationale: NULL represents an unknown/missing value and is not tested with = NULL.
Question 7
What removes duplicate result rows?
Correct Answer: B. DISTINCT
Rationale: SELECT DISTINCT removes duplicate selected-row combinations.
Question 8
Which operator tests an inclusive range?
Correct Answer: A. BETWEEN
Rationale: BETWEEN includes both endpoints.
WGU D427 Enhanced Study Guide | Original Practice Material Page 3
