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FC0-U71 Practice Question: A user is unable to insert a new record into a…
A user is unable to insert a new record into a database table because a required field is missing. Which database concept enforces that a field must have a value?
⚠ Common exam trap
Test-takers frequently confuse the NOT NULL constraint with the primary key, thinking that a primary key's uniqueness property is what enforces a required value, but the primary key's NOT NULL behavior is a side effect, not its defining purpose.
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
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NOT NULL constraint
A NOT NULL constraint is a database rule that prevents a field from containing a NULL value, ensuring that a value must be provided for that column when inserting or updating a record. In this scenario, the user cannot insert a new record because the required field is missing, which directly violates the NOT NULL constraint. This constraint is enforced at the database engine level, typically during the INSERT or UPDATE operation, and will raise an error if the field is omitted or set to NULL.
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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NOT NULL constraint
Why this is correct
A NOT NULL constraint prevents NULL values in a column, making it required.
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Primary key
Why it's wrong here
A primary key enforces uniqueness and non-null only on that specific column, not all fields.
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Index
Why it's wrong here
An index speeds up queries but does not enforce data integrity constraints like required fields.
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Foreign key
Why it's wrong here
A foreign key links tables and ensures referential integrity, not a general NOT NULL requirement.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.