This post is a part of the DP-900: Microsoft Azure Data Fundamentals Exam Prep Hub.
This topic falls under these sections:
Identify considerations for relational data on Azure (20–25%)
--> Describe relational concepts
--> Identify features of relational data
Note that there are 10 practice questions (with answers and explanations) for each section to help you solidify your knowledge of the material. Also, there are 2 practice tests with 60 questions each available on the hub below the exam topics section.
Relational data is one of the most fundamental concepts in data management and a core focus area for the DP-900 exam. Understanding how relational data is structured, stored, and accessed will help you confidently answer questions related to databases, querying, and Azure data services.
What Is Relational Data?
Relational data is data that is organized into tables (relations) consisting of:
- Rows (records)
- Columns (attributes or fields)
Each table represents a specific entity, such as customers, orders, or products. Relationships between tables are defined using keys.
Core Features of Relational Data
1. Tabular Structure (Rows and Columns)
Relational data is stored in a structured, tabular format:
- Each row represents a single record
- Each column represents a specific attribute
Example:
| CustomerID | Name | City |
|---|---|---|
| 1 | John | Seattle |
| 2 | Maria | Austin |
This structure makes relational data easy to query and understand.
2. Predefined Schema
Relational databases enforce a fixed schema, which defines:
- Table structure
- Column names
- Data types (e.g., INT, VARCHAR, DATE)
This ensures:
- Data consistency
- Data validation
- Predictable structure
3. Use of Keys
Keys are essential for uniquely identifying records and linking tables.
Primary Key
- Uniquely identifies each row in a table
- Cannot contain duplicate or null values
Example: CustomerID
Foreign Key
- Links one table to another
- Establishes relationships between tables
Example: Order.CustomerID → Customer.CustomerID
4. Relationships Between Tables
Relational data supports relationships such as:
- One-to-One
- One-to-Many
- Many-to-Many
Example:
- One customer can have many orders (one-to-many)
These relationships allow complex data models to be built efficiently.
5. Structured Query Language (SQL)
Relational data is accessed and manipulated using Structured Query Language (SQL).
SQL is used to:
- Query data (
SELECT) - Insert data (
INSERT) - Update data (
UPDATE) - Delete data (
DELETE)
Example:
SELECT Name FROM Customers WHERE City = 'Seattle';
6. Data Integrity and Constraints
Relational databases enforce data integrity through constraints such as:
- PRIMARY KEY
- FOREIGN KEY
- NOT NULL
- UNIQUE
- CHECK
These rules ensure that:
- Data is accurate
- Relationships remain valid
- Invalid data is prevented
7. Normalization
Relational data is often normalized to reduce redundancy and improve consistency.
Normalization involves:
- Splitting data into multiple related tables
- Eliminating duplicate data
- Ensuring dependencies are logical
Example:
Instead of storing customer details in every order row, store them in a separate Customers table.
8. ACID Transactions
Relational databases support ACID properties, ensuring reliable transactions:
- Atomicity → All or nothing
- Consistency → Valid state maintained
- Isolation → Transactions don’t interfere
- Durability → Changes persist
This is especially important for transactional workloads.
Relational Data in Azure
Azure provides several services for working with relational data:
Azure SQL Database
- Fully managed relational database
- Supports SQL queries
- High availability and scalability
- Ideal for OLTP applications
Azure Database for PostgreSQL
- Managed open-source relational database
- Supports PostgreSQL features and extensions
Azure Database for MySQL
- Managed MySQL database service
- Suitable for web and application workloads
These services support structured data, relationships, and SQL-based querying.
Why This Matters for DP-900
On the exam, you may be asked to:
- Identify characteristics of relational data
- Recognize table-based structures
- Understand keys and relationships
- Distinguish relational data from non-relational data
- Match relational workloads to Azure services
Summary — Exam-Relevant Takeaways
✔ Relational data is stored in tables (rows and columns)
✔ It uses a fixed schema with defined data types
✔ Primary and foreign keys define relationships
✔ Data is accessed using SQL
✔ Supports data integrity constraints
✔ Often normalized to reduce redundancy
✔ Ensures reliability with ACID transactions
✔ Common Azure services:
- Azure SQL Database
- Azure Database for PostgreSQL
- Azure Database for MySQL
Go to the Practice Exam Questions for this topic.
Go to the DP-900 Exam Prep Hub main page.
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