Implementing UUIDs and Auto Incrementing IDs in SQL and Azure SQL: Our Beginners Guide
Tags: azure, sql, microlearning, beginners
Published: 2023-12-11 09:19:32

**Introduction:** Universally Unique Identifiers (UUIDs) play a pivotal role in ensuring data uniqueness across diverse database systems, offering a standardised approach for generating unique identifiers. However, the implementation of UUIDs in SQL and Azure SQL comes with unique considerations. Additionally, the use of auto incrementing IDs, facilitated by the `IDENTITY` property, provides an essential mechanism for managing primary keys in relational databases.

**1. Data Type:** In both traditional SQL and Azure SQL, the `uniqueidentifier` data type is commonly employed for UUIDs. This ensures that each identifier is globally unique, making it a robust choice for various applications.

**2. Generation of UUIDs:**

- SQL: UUIDs can be generated using various methods, depending on the database system. While some systems offer built-in functions, others may require custom expressions to create these unique identifiers.

    ```SQL
 CREATE TABLE ExampleTable ( Id UUID PRIMARY KEY, 
Name VARCHAR(255) );
    ```

- Azure SQL: The `NEWID()` function is employed to generate UUIDs, providing a convenient and standardised approach.

    ```SQL
CREATE TABLE ExampleTable (Id UNIQUEIDENTIFIER DEFAULT NEWID()
PRIMARY KEY, 
Name NVARCHAR(255));
    ```

**3. Indexing:**

- SQL: Indexing UUIDs can pose challenges due to their inherent randomness, potentially leading to more frequent page splits. Careful consideration and planning of indexing strategies are crucial for optimal performance.

- Azure SQL: Similar to traditional SQL, indexing strategies should be planned to enhance performance in Azure SQL databases.

    ```SQL
CREATE INDEX IX_ExampleTable_Id ON ExampleTable (Id);
    ```

**4. Performance Considerations:**

- SQL and Azure SQL: The use of UUIDs as primary keys may impact performance, especially with large datasets. It is essential to evaluate performance implications in scenarios involving frequent data access or sizable tables.

**5. Default Values:**

- SQL and Azure SQL: Default values for UUID columns may need to be explicitly set to ensure proper data handling.

```SQL
CREATE TABLE ExampleTable (Id UNIQUEIDENTIFIER DEFAULT NEWID(),
Name NVARCHAR(255) );
```

**6. Storage Size:** Both SQL and Azure SQL databases typically allocate 16 bytes for storing UUIDs, maintaining a standardized size across systems.

**7. Compatibility and Standards:**

- SQL: While UUIDs are generally supported in various SQL databases, specific implementation details may vary. Understanding these variations is crucial for consistent behavior.
- Azure SQL: Adhering to SQL standards, Azure SQL ensures compatibility with UUID implementations across different database systems.

**8. Azure-Specific Features:** Azure SQL introduces additional features beyond traditional SQL, providing enhanced management and security options for databases.

**Auto Incrementing IDs:**

**Creating a Table with Auto Increment:** Auto incrementing IDs, powered by the `IDENTITY` property, offer a streamlined solution for managing primary keys, ensuring each record receives a unique identifier automatically.

```SQL
CREATE TABLE Employees (EmployeeID int IDENTITY(1,1)PRIMARY KEY, 
Name varchar(255) );
```

**Inserting Data:** During data insertion, there is no need to manually assign values to auto incrementing fields, simplifying the process.

```SQL
INSERT INTO Employees (Name) VALUES ('John Doe');
```

**JPA Implementation:** For Java Persistence API (JPA) users, the `@GeneratedValue` annotation with the `GenerationType.IDENTITY` strategy enables seamless integration of auto incrementing IDs.

```JAVA
@Entity 
@Table 
public class Employee {

@Id     
@GeneratedValue(strategy=GenerationType.IDENTITY)     
private Long id; 
     
@NotNull     
private String name; }
```


**Conclusion:** Implementing UUIDs and auto incrementing IDs in SQL and Azure SQL involves understanding the nuances of data types, generation methods, indexing strategies, and performance considerations. Balancing the advantages of UUIDs for global uniqueness with the efficiency of auto incrementing IDs ensures a comprehensive approach to managing primary keys in relational databases. Consider specific database requirements and refer to documentation for accurate implementation details tailored to your chosen database system.

---
## Contributors
Marisa Pinheiro
[LinkedIn](https://www.linkedin.com/in/marisa-pinheiro-833a12113/) [Github](https://github.com/Marisa-Pinheiro)
Colin Nordmark
[LinkedIn](https://www.linkedin.com/in/colinnordmark/)  [Github](https://github.com/colinnordmark)
For more information, check out [Quickipedia](https://github.com/ComplotTeam/Quickipedia)!