DA0-002 Data Concepts and Environments Practice Question
A database has a table 'Orders' with columns OrderID (PK), CustomerID, OrderDate, and a table 'OrderDetails' with OrderID (FK), ProductID, Quantity. To ensure that every OrderID in OrderDetails exists in Orders, which integrity constraint is enforced?
⚠ Common exam trap
Many candidates confuse the four integrity types—candidates often pick 'entity integrity' because it sounds like it relates to keys, but entity integrity is specifically about primary keys, not foreign keys.
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
✓
Referential integrity
Referential integrity ensures that a foreign key value in a child table (OrderDetails.OrderID) must match an existing primary key value in the parent table (Orders.OrderID) or be NULL. This constraint prevents orphaned records and maintains consistent relationships between tables. Since OrderDetails.OrderID is defined as a foreign key referencing Orders, the database enforces referential integrity to guarantee every OrderID in OrderDetails exists in Orders.
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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Entity integrity
Why it's wrong here
Entity integrity requires primary keys to be unique and non-null within a single table, so it cannot enforce cross-table matching. Referential integrity is the constraint ensuring every OrderDetails.OrderID exists in Orders; entity integrity would suit preventing duplicate OrderID values.
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Domain integrity
Why it's wrong here
Domain integrity constrains column values to a permitted set or data type, not cross-table row existence. Referential integrity governs the foreign key relationship ensuring each OrderDetails.OrderID exists in Orders; domain constraints would suit validating Quantity ranges.
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User-defined integrity
Why it's wrong here
User-defined integrity enforces bespoke business rules, not the parent-child row matching between Orders and OrderDetails. The stem describes a foreign key referencing a primary key, which is referential integrity. User-defined integrity would be correct for a custom rule such as Quantity never exceeding 100, which no built-in constraint type covers.
- ✓
Referential integrity
Why this is correct
Referential integrity guarantees that every foreign key value in OrderDetails matches an existing primary key in Orders, preventing orphaned detail rows. This directly enforces the stem's requirement that each OrderID in OrderDetails exists in the parent Orders table.
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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 DA0-002 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 DA0-002 exam.