FC0-U71 Data and Database Fundamentals Practice Question
A company needs to store customer orders and ensure that each order is uniquely identified. Which database concept should be used?
⚠ Common exam trap
The trap is confusing the general concept of a constraint with the specific primary key constraint — candidates must recognize that while a primary key is a constraint, the question asks for the concept that uniquely identifies each row, which is the primary key.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Primary key
A primary key is a column (or set of columns) that uniquely identifies each row in a table, which is exactly what is needed to ensure each customer order has a unique identifier. Primary keys enforce uniqueness and cannot contain NULL values, guaranteeing every order record is distinguishable.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Constraint
Why it's wrong here
A constraint is the general category of column rules; it does not itself identify rows uniquely. It is tempting because primary keys and unique constraints are constraint types, but the specific concept guaranteeing each order's unique identifier is the primary key, not the umbrella term.
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Index
Why it's wrong here
An index accelerates query lookups on a column but does not enforce uniqueness unless declared unique, so duplicate order identifiers remain possible. It is tempting because indexes are commonly created on identifier columns, yet a primary key is what actually guarantees each order's unique identification.
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Foreign key
Why it's wrong here
A foreign key enforces referential integrity between tables, linking an order to its customer; it does not guarantee that each order row is unique. It is tempting because orders reference customers, but uniqueness requires a primary key, which foreign keys merely point to.
- ✓
Primary key
Why this is correct
A primary key enforces uniqueness on one or more columns and rejects duplicate or null values, so every customer order row is uniquely identified. It satisfies the stated requirement for guaranteed unique identification, unlike other keys or indexes that permit duplicates or serve only performance purposes.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This FC0-U71 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the FC0-U71 exam.