How Can I Log the SQL Statements That Modify a Specific Table in SQL Server 2008?

Logging SQL that Affected a Table

To determine the source of updates to a column, you can create a trigger on the affected table that captures the SQL responsible for the changes. Let's explore how to achieve this in Microsoft SQL Server 2008.

Creating the Trigger

Utilizing a DDL statement, you can create a trigger that logs the SQL for table updates:

CREATE TRIGGER trigger_name ON table_name
AFTER UPDATE
AS
BEGIN
    -- Declare a variable to store the executed SQL
    DECLARE @sql_text VARCHAR(MAX);
    
    -- Retrieve the executed SQL from the context_info() function
    SET @sql_text = CAST(EVENTDATA() AS NVARCHAR(MAX));
    
    -- Insert the SQL text into a log table or perform other desired actions
    INSERT INTO log_table (sql_text) VALUES (@sql_text);
END;

Accessing the Executed SQL

Once the trigger is created, the EVENTDATA() function can be used within the trigger code to capture the executed SQL. The EVENTDATA() function provides access to information about the current database event, including the SQL text that caused it. By extracting this information, you can identify the source of the column updates.

Additional Notes:

• Remember to replace trigger_name, table_name, and log_table with appropriate values for your specific scenario.
• You can customize the trigger to perform additional actions, such as sending an email or writing to a file, depending on your requirements.
• Consider performance implications when using triggers. They can potentially have an impact on the database's overall responsiveness.

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