The answer is a relational database. This is the correct choice because the scenario explicitly requires performing complex queries that join customer and order data, which is the core strength of relational databases. They enforce a fixed schema with tables, primary keys, and foreign keys, enabling efficient JOIN operations using SQL while ensuring data integrity and ACID transactions for accurate order history. On the Microsoft Azure Data Fundamentals DP-900 exam, this question tests your ability to match workload requirements to the appropriate Azure data store; a common trap is choosing a NoSQL option like Cosmos DB, which lacks native support for complex joins across related tables. Remember the memory tip: if you need to JOIN two tables, you need a relational database—think “JOIN = relational.”
DP-900 Describe core data concepts Practice Question
This DP-900 practice question tests your understanding of describe core data concepts. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 names, addresses, and order history. They need to perform complex queries that join customer and order data. Which type of data store is most appropriate for this scenario?
Why wrong: Key-value stores are designed for simple lookups by key and do not support complex join queries across multiple datasets.
B
Relational database
Relational databases organize data into tables with defined schemas and support SQL queries including joins, making them ideal for this requirement.
C
Document database
Why wrong: Document databases store semi-structured data (e.g., JSON) and although they can embed related data, they are not optimized for join-heavy queries across collections.
D
Graph database
Why wrong: Graph databases are built for highly interconnected data and relationship traversal, but they are not the standard choice for tabular join operations typical of relational workloads.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Relational database
A relational database (e.g., Azure SQL Database) is most appropriate because the scenario requires joining customer and order data via complex queries. Relational databases enforce a fixed schema with tables, primary keys, and foreign keys, enabling efficient JOIN operations using SQL. This structure ensures data integrity and supports ACID transactions, which are essential for accurate order history and customer records.
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.
✗
Key-value store
Why it's wrong here
Key-value stores are designed for simple lookups by key and do not support complex join queries across multiple datasets.
✓
Relational database
Why this is correct
Relational databases organize data into tables with defined schemas and support SQL queries including joins, making them ideal for this requirement.
Related concept
Read the scenario before looking for a memorised answer.
✗
Document database
Why it's wrong here
Document databases store semi-structured data (e.g., JSON) and although they can embed related data, they are not optimized for join-heavy queries across collections.
✗
Graph database
Why it's wrong here
Graph databases are built for highly interconnected data and relationship traversal, but they are not the standard choice for tabular join operations typical of relational workloads.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose a document database (Option C) because they associate 'complex queries' with JSON flexibility, but fail to recognize that 'joining' specifically requires relational database features like SQL JOINs and foreign keys, which document stores lack.
Detailed technical explanation
How to think about this question
Under the hood, relational databases use B-tree indexes and query optimizers to resolve JOINs via hash, merge, or nested-loop algorithms. For example, a JOIN between Customers and Orders tables leverages foreign key indexes to avoid full table scans. In a real-world scenario, a document database would require application-side joins or denormalization, leading to data duplication and eventual consistency issues, whereas a relational database ensures immediate consistency and referential integrity via foreign key constraints.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: Relational database — A relational database (e.g., Azure SQL Database) is most appropriate because the scenario requires joining customer and order data via complex queries. Relational databases enforce a fixed schema with tables, primary keys, and foreign keys, enabling efficient JOIN operations using SQL. This structure ensures data integrity and supports ACID transactions, which are essential for accurate order history and customer records.
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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