Temporal tables in Azure SQL Database allow you to track historical changes to data automatically, enabling point-in-time analysis and compliance scenarios. This feature, also known as system-versioned temporal tables, maintains a full history of every row modification, making it easier to audit changes and recover previous states.
When a temporal table is enabled, Azure SQL Database automatically creates a paired history table that stores all previous versions of rows. The system timestamps each change with the transaction's start time, so you can query the table with a FOR SYSTEM_TIME clause to see the data as it existed at any moment in the past.
Key benefits include:
- Data auditing: Easily track who changed what and when.
- Time-travel queries: Retrieve data as it appeared at a specific point in time.
- Compliance: Meet regulatory requirements for data retention and historical reporting.
To create a temporal table, you define two DATETIME2 columns for the system period (e.g., SysStartTime and SysEndTime) and use the GENERATED ALWAYS AS ROW START/END syntax. The PERIOD FOR SYSTEM_TIME clause marks these columns, and the WITH (SYSTEM_VERSIONING = ON) option enables versioning.
Temporal tables integrate seamlessly with existing tools, requiring no changes to application queries for current data. For developers and DBAs preparing for certifications like DP-800 or DP-700, mastering temporal tables is a valuable skill in modern Azure data solutions.