DP-900 Describe core data concepts Practice Question
A company stores customer data in a relational table with fixed columns: CustomerID (integer), FirstName (string), LastName (string), Email (string). They also store product images as JPEG files, and customer feedback as JSON documents that may contain varying fields such as rating, comment, and optional metadata. Which of the following correctly orders these data types from most structured to least structured?
⚠ Common exam trap
It's easy for candidates to confuse semi-structured data (JSON) with unstructured data (JPEG), mistakenly thinking JSON is unstructured because its fields can vary, when in fact it retains a key-value structure that makes it semi-structured.
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
✓
Relational table, JSON documents, JPEG files
The relational table is the most structured because it enforces a fixed schema with predefined columns and data types (e.g., CustomerID integer, FirstName string). JSON documents are semi-structured: they have a flexible schema where fields like rating and comment can vary per document, but they still provide key-value organization. JPEG files are unstructured binary data with no internal schema or queryable structure, making them the least structured.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
JSON documents, relational table, JPEG files
Why it's wrong here
Starting with JSON documents before the relational table inverts the structured data hierarchy. A relational table is the canonical structured data model: its schema is defined in advance, every row shares the same columns, and relationships are enforced via constraints and joins, giving it the highest degree of structure. JSON documents are semi-structured because each document can have a different set of keys, nested levels, and value types; while keys give some order, there is no predefined, uniform schema. Putting JSON ahead of the relational table suggests JSON is more structured, but it is actually less structured because its flexible, self-describing nature allows schema drift and variability. The correct order should place the fixed relational schema first, which makes this option wrong.
When this WOULD be correct
If the question asked to order data types from least to most structured, then JSON documents (semi-structured) would come before relational tables (structured), making A correct.
- ✓
Relational table, JSON documents, JPEG files
Why this is correct
A relational table is the most structured here because it enforces a fixed schema: each row (customer record) must conform to predefined columns, data types, and constraints such as primary keys or NOT NULL, enabling rigorous integrity and efficient querying. JSON documents are semi-structured because they consist of key-value pairs and nested objects that can vary across documents—there is no required uniform schema, but the names and types of fields provide intrinsic structure. JPEG files are unstructured binary data; their pixel and compression bytes contain no self-describing fields that a database query engine can interpret as discrete attributes. Thus the descending order fixed-schema table → flexible-schema JSON → schema-less binary JPEG is correct.
- ✗
JPEG files, JSON documents, relational table
Why it's wrong here
This sequence is the exact reverse of the correct ordering, placing the least structured format first and the most structured last. Relational tables have the highest structure—they enforce a fixed schema with typed columns, relationships, and constraints, whereas JSON documents are only semi-structured, with flexible fields and nested objects that vary by document, and JPEG files are unstructured binary data with no queryable attributes. Reversing these categories implies that a JPEG image is more structured than a self-describing JSON object and that a relational table is the least structured, which contradicts the fundamental definitions of data types used in Azure data solutions. Because the progression should be from unstructured to semi-structured to structured (JPEG → JSON → relational), this backwards order is incorrect.
When this WOULD be correct
If the question asked to order from least structured to most structured, then C (JPEG files, JSON documents, relational table) would be correct.
- ✗
Relational table, JPEG files, JSON documents
Why it's wrong here
This ordering incorrectly ranks unstructured JPEG data above semi-structured JSON. A JPEG file is a compressed binary representation of an image—its internal bytes (e.g., JFIF markers, DCT coefficients) are meaningless as discrete business attributes without specialized decoding, making it truly unstructured. JSON documents, by contrast, contain named fields, values, and arrays that are directly parseable and queryable by systems like Azure Cosmos DB; even if no schema is enforced, the content itself is self-describing. Since semi-structured data sits between unstructured and structured, a JPEG cannot precede JSON in a 'less structured to more structured' ranking—rather, it must come after. Therefore, this sequence misplaces the two, making it incorrect.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The DP-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Relational table, JSON documents, JPEG filesCorrect answer▾
Why this is correct
A relational table is the most structured here because it enforces a fixed schema: each row (customer record) must conform to predefined columns, data types, and constraints such as primary keys or NOT NULL, enabling rigorous integrity and efficient querying. JSON documents are semi-structured because they consist of key-value pairs and nested objects that can vary across documents—there is no required uniform schema, but the names and types of fields provide intrinsic structure. JPEG files are unstructured binary data; their pixel and compression bytes contain no self-describing fields that a database query engine can interpret as discrete attributes. Thus the descending order fixed-schema table → flexible-schema JSON → schema-less binary JPEG is correct.
✗JSON documents, relational table, JPEG filesWrong answer — click to see why▾
Why this is wrong here
JSON documents are semi-structured (varying fields), not more structured than a relational table (fixed schema). JPEG files are unstructured binary data, so they are the least structured.
★ When this WOULD be the correct answer
If the question asked to order data types from least to most structured, then JSON documents (semi-structured) would come before relational tables (structured), making A correct.
Why candidates choose this
Candidates may think JSON is more structured than a relational table because it has key-value pairs, overlooking that relational tables enforce a fixed schema while JSON allows flexible fields.
✗JPEG files, JSON documents, relational tableWrong answer — click to see why▾
Why this is wrong here
JPEG files are unstructured binary data, JSON documents are semi-structured (schema-on-read), and relational tables are structured (fixed schema). Ordering from most to least structured should be relational table, JSON documents, JPEG files, not JPEG first.
★ When this WOULD be the correct answer
If the question asked to order from least structured to most structured, then C (JPEG files, JSON documents, relational table) would be correct.
Why candidates choose this
Candidates might mistakenly think JSON is more structured than relational tables because JSON has nested keys, or they may confuse 'structured' with 'complexity' or 'flexibility'.
Analysis generated from the official DP-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
Table
A table is a structured collection of data organized into rows and columns, used in databases and spreadsheets to store and manage information efficiently.
Key term
Schema
A schema is a blueprint or logical structure that defines how data is organized, stored, and accessed in a database or information system.
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