WGU C170 Data Management Applications OA Exam Actual
Exam 2026/2027 – Complete Objective Assessment with
Detailed Rationales | 100% Verified | Pass Guaranteed – A+
Graded
Section A: Relational Database Concepts & Design Fundamentals
Q1: A university database table contains StudentID, SSN, Email, and Major. Which
attribute combination represents a superkey but not necessarily a candidate key?
A. StudentID alone
B. {StudentID, Email}
C. {StudentID, SSN, Email, Major} [CORRECT]
D. SSN alone
Correct Answer: C
Rationale: A superkey is any set of attributes that uniquely identifies a row; {StudentID,
SSN, Email, Major} is a superkey but not minimal, so it is not a candidate key. StudentID
(A) and SSN (D) are minimal superkeys (candidate keys), and {StudentID, Email} (B) is
also a superkey but may or may not be minimal depending on keys.
Q2: In a relational database, referential integrity requires that:
A. Every table must have a composite primary key
B. A foreign key value must either match a primary key value in the referenced table or
be NULL [CORRECT]
C. No two rows can have the same values in any column
D. All attributes must contain atomic values
Correct Answer: B
Rationale: Referential integrity ensures foreign keys reference existing primary keys or
are NULL; composite keys (A) are not required, unique rows (C) describe entity integrity
via keys, and atomic values (D) describe 1NF.
Q3: A database administrator needs to produce a horizontal subset of rows from the
EMPLOYEE table where Department = 'Sales'. Which relational algebra operation
accomplishes this?
,A. PROJECT
B. UNION
C. SELECT [CORRECT]
D. PRODUCT
Correct Answer: C
Rationale: The SELECT operation (σ) performs horizontal subsetting based on a
predicate; PROJECT (A) is vertical column selection, UNION (B) combines relations, and
PRODUCT (D) is the Cartesian product.
Q4: The relational algebra PROJECT operation (π) is best described as:
A. Combining two tables based on a related column
B. Returning only rows that satisfy a specific condition
C. Producing a vertical subset of columns and eliminating duplicate tuples [CORRECT]
D. Returning the difference between two tables
Correct Answer: C
Rationale: PROJECT selects specific columns and removes duplicates; JOIN (A)
combines tables, SELECT (B) filters rows, and DIFFERENCE (D) returns rows in one table
but not another.
Q5: Entity integrity in a relational database dictates that:
A. Foreign key values may never be NULL
B. No primary key attribute can contain NULL values [CORRECT]
C. All columns must have DEFAULT values specified
D. Every table must participate in at least one relationship
Correct Answer: B
Rationale: Entity integrity requires primary keys to be unique and non-NULL; foreign keys
(A) can be NULL, DEFAULT values (C) are optional, and standalone tables (D) are
permitted.
Q6: The system catalog (data dictionary) in a relational database management system
stores:
A. Only user query logs and execution times
B. Metadata describing database structure such as table names, column definitions,
constraints, and relationships [CORRECT]
C. Backup copies of all user data
D. Operating system configuration files
, Correct Answer: B
Rationale: The system catalog stores metadata about database objects; query logs (A)
are separate, backups (C) are external, and OS files (D) are outside the DBMS.
Q7: A foreign key in a relational table serves to:
A. Automatically encrypt sensitive column data
B. Establish a logical link between two relations and enforce referential integrity
[CORRECT]
C. Guarantee that all values in a column are unique
D. Create an automatic index on the primary key
Correct Answer: B
Rationale: Foreign keys link tables and enforce referential integrity; encryption (A) is not
a foreign key function, uniqueness (C) is enforced by UNIQUE/PRIMARY KEY
constraints, and automatic indexing (D) is implementation-dependent.
Q8: In relational database terminology, a domain refers to:
A. The physical server hosting the database
B. The set of valid data types available in SQL
C. The set of permissible values for a given attribute [CORRECT]
D. The network protocol used for client connections
Correct Answer: C
Rationale: A domain defines the set of valid values for an attribute; it is not a server (A),
data type list (B), or network protocol (D).
Q9: Two relations, R and S, each contain 5 rows. The Cartesian PRODUCT of R and S will
contain:
A. 5 rows
B. 10 rows
C. 25 rows [CORRECT]
D. 5^5 rows
Correct Answer: C
Rationale: The Cartesian product R × S contains m × n rows (5 × 5 = 25); UNION (A, B)
would combine rows with duplicates eliminated, and 5^5 (D) is incorrect.
Q10: The relational algebra operation that returns rows common to both relations R and
S is:
Exam 2026/2027 – Complete Objective Assessment with
Detailed Rationales | 100% Verified | Pass Guaranteed – A+
Graded
Section A: Relational Database Concepts & Design Fundamentals
Q1: A university database table contains StudentID, SSN, Email, and Major. Which
attribute combination represents a superkey but not necessarily a candidate key?
A. StudentID alone
B. {StudentID, Email}
C. {StudentID, SSN, Email, Major} [CORRECT]
D. SSN alone
Correct Answer: C
Rationale: A superkey is any set of attributes that uniquely identifies a row; {StudentID,
SSN, Email, Major} is a superkey but not minimal, so it is not a candidate key. StudentID
(A) and SSN (D) are minimal superkeys (candidate keys), and {StudentID, Email} (B) is
also a superkey but may or may not be minimal depending on keys.
Q2: In a relational database, referential integrity requires that:
A. Every table must have a composite primary key
B. A foreign key value must either match a primary key value in the referenced table or
be NULL [CORRECT]
C. No two rows can have the same values in any column
D. All attributes must contain atomic values
Correct Answer: B
Rationale: Referential integrity ensures foreign keys reference existing primary keys or
are NULL; composite keys (A) are not required, unique rows (C) describe entity integrity
via keys, and atomic values (D) describe 1NF.
Q3: A database administrator needs to produce a horizontal subset of rows from the
EMPLOYEE table where Department = 'Sales'. Which relational algebra operation
accomplishes this?
,A. PROJECT
B. UNION
C. SELECT [CORRECT]
D. PRODUCT
Correct Answer: C
Rationale: The SELECT operation (σ) performs horizontal subsetting based on a
predicate; PROJECT (A) is vertical column selection, UNION (B) combines relations, and
PRODUCT (D) is the Cartesian product.
Q4: The relational algebra PROJECT operation (π) is best described as:
A. Combining two tables based on a related column
B. Returning only rows that satisfy a specific condition
C. Producing a vertical subset of columns and eliminating duplicate tuples [CORRECT]
D. Returning the difference between two tables
Correct Answer: C
Rationale: PROJECT selects specific columns and removes duplicates; JOIN (A)
combines tables, SELECT (B) filters rows, and DIFFERENCE (D) returns rows in one table
but not another.
Q5: Entity integrity in a relational database dictates that:
A. Foreign key values may never be NULL
B. No primary key attribute can contain NULL values [CORRECT]
C. All columns must have DEFAULT values specified
D. Every table must participate in at least one relationship
Correct Answer: B
Rationale: Entity integrity requires primary keys to be unique and non-NULL; foreign keys
(A) can be NULL, DEFAULT values (C) are optional, and standalone tables (D) are
permitted.
Q6: The system catalog (data dictionary) in a relational database management system
stores:
A. Only user query logs and execution times
B. Metadata describing database structure such as table names, column definitions,
constraints, and relationships [CORRECT]
C. Backup copies of all user data
D. Operating system configuration files
, Correct Answer: B
Rationale: The system catalog stores metadata about database objects; query logs (A)
are separate, backups (C) are external, and OS files (D) are outside the DBMS.
Q7: A foreign key in a relational table serves to:
A. Automatically encrypt sensitive column data
B. Establish a logical link between two relations and enforce referential integrity
[CORRECT]
C. Guarantee that all values in a column are unique
D. Create an automatic index on the primary key
Correct Answer: B
Rationale: Foreign keys link tables and enforce referential integrity; encryption (A) is not
a foreign key function, uniqueness (C) is enforced by UNIQUE/PRIMARY KEY
constraints, and automatic indexing (D) is implementation-dependent.
Q8: In relational database terminology, a domain refers to:
A. The physical server hosting the database
B. The set of valid data types available in SQL
C. The set of permissible values for a given attribute [CORRECT]
D. The network protocol used for client connections
Correct Answer: C
Rationale: A domain defines the set of valid values for an attribute; it is not a server (A),
data type list (B), or network protocol (D).
Q9: Two relations, R and S, each contain 5 rows. The Cartesian PRODUCT of R and S will
contain:
A. 5 rows
B. 10 rows
C. 25 rows [CORRECT]
D. 5^5 rows
Correct Answer: C
Rationale: The Cartesian product R × S contains m × n rows (5 × 5 = 25); UNION (A, B)
would combine rows with duplicates eliminated, and 5^5 (D) is incorrect.
Q10: The relational algebra operation that returns rows common to both relations R and
S is:
