Creating Audit Trails Using SQL Server Change Data Capture
By Tom Nonmacher
Welcome to SQLSupport.org’s blog! Today, we’ll be delving into the realm of creating audit trails using SQL Server Change Data Capture (CDC). In the world of database administration, it’s crucial to have the capability to track changes made to your data over time. With the use of Change Data Capture technology in SQL Server 2016 and 2017, MySQL 5.7, DB2 11.1, and Azure SQL, you can keep a comprehensive record of all the insertions, updates, and deletions carried out in your database.
To start off, let's talk about SQL Server 2016 and 2017. The Change Data Capture feature in these versions of SQL Server is a system function that records insert, update, and delete activity applied to SQL Server tables, and makes the details of the changes available in an easily consumed relational format. The Change Data Capture functionality can be enabled for your tables using a simple T-SQL command.
EXEC sys.sp_cdc_enable_table
@source_schema = N'dbo',
@source_name = N'MyTable',
@role_name = NULL,
@supports_net_changes = 1
GO
MySQL 5.7 also has a similar feature, albeit under a different name - the Binary Log. This log contains “events” that describe database changes such as table creation operations or changes to table data. It also contains events for statements that potentially could have made changes (for example, a DELETE which matched no rows), unless row-based logging is used. Here's how to enable binary logging.
mysql> SET sql_log_bin = 1;
DB2 11.1 brings a comparable feature to the table called the AUDIT facility. It collects data about the execution of SQL statements and database activities, providing a detailed trail of actions that are performed on the database. This is how you would enable auditing for all actions carried out by a specific user.
db2> AUDIT USER user1 BY ACCESSING STATUS BOTH ERROR TYPE AUDIT TO /home/user1/auditlogs
Finally, Azure SQL provides a built-in feature called Auditing for Azure SQL Database and Azure Synapse Analytics. Enabling this feature will track database events and write them to an audit log in your Azure storage account. Azure auditing can be enabled using the Azure portal, PowerShell, or T-SQL. Here's an example of how to enable auditing using T-SQL commands.
EXECUTE sp_Azure_Audit_Setup
@database_name = N'myDatabase',
@audit_action_type = 1,
@audit_action_name = N'Delete',
@audit_target_type = 1,
@audit_target_name = N'myAuditTarget',
@audit_specification_name = N'myAuditSpec',
@audit_file_path = N'myStorageAccount.blob.core.windows.net/myAuditContainer';
As you can see, each of these technologies provides a unique and powerful way to create audit trails in your databases. Through the use of CDC, Binary Log, AUDIT facility, and Azure Auditing, you can confidently track, record, and manage all changes to your data. These features not only aid in maintaining data integrity and security, but also assist in troubleshooting and performance tuning. So go ahead, implement these tools in your database management system and keep your data trail clear and accountable!