Referential integrity is the correct data concept because it defines the rule that every order must be linked to a valid, existing customer ID, ensuring that relationships between tables remain consistent. In a relational database, this is enforced through a foreign key constraint, which prevents orphaned records by requiring that each value in the order’s customer ID column matches a primary key value in the Customers table. On the Microsoft Azure Data Fundamentals DP-900 exam, this concept tests your understanding of how foreign keys maintain data consistency across related tables, often appearing in scenario-based questions about preventing invalid data entries. A common trap is confusing referential integrity with entity integrity (which focuses on unique primary keys) or domain integrity (which restricts data types and ranges). To remember it, think of the mnemonic “FK = Family Key” — just as a family member must belong to an existing household, a foreign key value must belong to an existing primary key.
DP-900 Describe core data concepts Practice Question
This DP-900 practice question tests your understanding of describe core data concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company stores customer data in a relational database. The database design includes a rule that every order must be associated with a valid customer ID that exists in the Customers table. This rule is an example of which data concept?
Referential integrity uses foreign keys to ensure values in one table match primary keys in another, exactly as described.
B
Data normalization
Why wrong: Normalization is the process of reducing data redundancy and improving data integrity, not specifically about enforcing foreign key relationships.
C
Entity integrity
Why wrong: Entity integrity ensures that the primary key is unique and not null, not about cross-table constraints.
D
Data consistency
Why wrong: Data consistency is a broader concept that ensures data is accurate and valid, but the specific rule described is referential integrity.
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 relationships between tables remain consistent. In a relational database, a foreign key constraint enforces that every order's customer ID must match an existing customer ID in the Customers table, preventing orphaned records. This rule directly implements referential integrity as defined by the SQL standard (e.g., via FOREIGN KEY constraints).
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Referential integrity
Why this is correct
Referential integrity uses foreign keys to ensure values in one table match primary keys in another, exactly as described.
Related concept
Read the scenario before looking for a memorised answer.
✗
Data normalization
Why it's wrong here
Normalization is the process of reducing data redundancy and improving data integrity, not specifically about enforcing foreign key relationships.
✗
Entity integrity
Why it's wrong here
Entity integrity ensures that the primary key is unique and not null, not about cross-table constraints.
✗
Data consistency
Why it's wrong here
Data consistency is a broader concept that ensures data is accurate and valid, but the specific rule described is referential integrity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse referential integrity with entity integrity, mistakenly thinking that any rule involving a 'valid ID' is about primary keys, when in fact it is about foreign key relationships between tables.
Detailed technical explanation
How to think about this question
Under the hood, referential integrity is enforced by the database engine through foreign key constraints, which maintain a link between the foreign key column(s) in the child table and the primary key or unique key in the parent table. When an INSERT or UPDATE is attempted on the child table, the engine checks the parent table for a matching key; if none exists, the operation is rejected with an error (e.g., SQLSTATE 23503 in PostgreSQL). A real-world scenario is an e-commerce system where deleting a customer with existing orders would violate referential integrity unless cascading actions (ON DELETE CASCADE) are defined.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-900 question in full detail.
Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Referential integrity — Referential integrity ensures that relationships between tables remain consistent. In a relational database, a foreign key constraint enforces that every order's customer ID must match an existing customer ID in the Customers table, preventing orphaned records. This rule directly implements referential integrity as defined by the SQL standard (e.g., via FOREIGN KEY constraints).
What should I do if I get this DP-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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