C175 Fundamentals of Database Management Systems Objective Assessment Study Guide (2026/2027) | WGU Exam Review

,Question 1: Relational Keys & Integrity

Which type of database constraint ensures that every foreign key value in a child table matches a
valid, existing primary key value in the parent table (or is entirely NULL)?

• A. Entity Integrity
• B. Referential Integrity
• C. Domain Integrity
• D. Atomicity Constraint

Correct Answer: B. Referential Integrity

Rationale: Referential integrity guarantees that relationships between tables remain consistent
by ensuring foreign key references point to actual primary key records in parent tables.

Question 2: Normalization

A relational table contains customer order details where non-key attributes depend on other non-
key attributes rather than directly on the primary key (transitive dependency). To achieve Third
Normal Form (3NF), what action must be taken?

• A. Remove all repeating attribute groups.
• B. Split the table to remove the transitive dependency into a separate table.
• C. Convert the primary key into a composite key.
• D. Eliminate all foreign key constraints.

Correct Answer: B. Split the table to remove the transitive dependency into a separate
table.

Rationale: 3NF requires a table to be in 2NF with no transitive dependencies. Non-key attributes
dependent on other non-key attributes must be moved to a new relation.

Question 3: SQL Data Retrieval

Which SQL clause is used in conjunction with aggregate functions (like SUM() or COUNT()) to
filter groups of summary rows based on a specified condition?

• A. WHERE
• B. HAVING
• C. ORDER BY
• D. LIMIT

Correct Answer: B. HAVING

Rationale: The WHERE clause filters individual rows before aggregation, whereas the HAVING
clause filters summarized groups after GROUP BY execution.

,Question 4: ER Modeling Cardinality

In a university database, a single student can enroll in multiple courses, and a single course can
have multiple students enrolled. What type of binary relationship is this, and how is it typically
implemented in a relational database?

• A. One-to-One; implemented using a shared primary key.
• B. One-to-Many; implemented by placing the course ID as a foreign key in the student
table.
• C. Many-to-Many; implemented using an associative (junction) table containing foreign
keys from both entities.
• D. Recursive; implemented using self-referencing triggers.

Correct Answer: C. Many-to-Many; implemented using an associative (junction) table
containing foreign keys from both entities.

Rationale: Many-to-many relationships cannot be modeled directly with a foreign key in
relational tables; they require an associative junction table to resolve the relationship.

Question 5: DDL vs. DML

Which SQL statement belongs to the Data Definition Language (DDL) category used to modify
database structure?

• A. SELECT * FROM Employees;
• B. INSERT INTO Customers VALUES ('John', 'Doe');
• C. ALTER TABLE Products ADD DiscountPrice DECIMAL(10,2);
• D. UPDATE Orders SET Status = 'Shipped';

Correct Answer: C. ALTER TABLE Products ADD DiscountPrice DECIMAL(10,2);

Rationale: ALTER TABLE is a DDL command used to change schema structure, whereas SELECT,
INSERT, and UPDATE are DML commands used for data manipulation.

Question 6

What is the primary drawback of traditional file systems compared to modern Database
Management Systems (DBMS)?

• A. Elimination of data redundancy
• B. Data redundancy and data inconsistency
• C. Complete program-data independence
• D. Centralized hardware security

Correct Answer: B. Data redundancy and data inconsistency

, Rationale: File systems store data in independent, isolated files, leading to duplicated
data across files (redundancy) and conflicting versions of the same data
(inconsistency).

Question 7

What type of data integrity constraint ensures that every primary key column contains a
unique value and cannot be left null?

• A. Referential Integrity
• B. Entity Integrity
• C. Domain Integrity
• D. Logical Integrity

Correct Answer: B. Entity Integrity

Rationale: Entity integrity requires that every table have a primary key, and the
column(s) chosen as the primary key must be unique and non-null (NOT NULL).

Question 8

Which term describes an attribute or combination of attributes that uniquely identifies a
specific row within a relation?

• A. Foreign Key
• B. Candidate Key
• C. Secondary Index
• D. Junction Attribute

Correct Answer: B. Candidate Key

Rationale: A candidate key is any column or minimal set of columns that can uniquely
identify a tuple. A primary key is simply one candidate key chosen by the designer.

Question 9

In a relational database, what is the intersection of a row and a column called?

• A. Relation
• B. Attribute
• C. Tuple / Cell
• D. Schema

Correct Answer: C. Tuple / Cell