Why are unchanged columns showing up in the Audit Report?

After you enable auditing for columns and view the audit report, the newly audit-enabled columns show up in the audit report, even if you haven’t changed the values in the columns.

This happens because, before the columns are enabled for auditing, changes (if any) in those columns aren’t written to the audit table. After auditing is enabled, these columns are also added to the audit table, and displayed in the audit report.

For example, consider three columns, say, C1, C2, and C3, created on 1 Jan 2023. You add values in C1 and C2 columns.

Your database table displays these values.

C1	C2	C3	Last Update Date
c1value1	c2value1	null	01-Jan-2023

You enable auditing only for the C1 column, so the corresponding audit table will have these values.

Remember, the Last Update Date column is always audited.

C1	C2	C3	Last Update Date
c1value1	null	null	01-Jan-2023

Three months later, you update the value in the C1 column and add a value in the C3 column.

Database table will have these values.

C1	C2	C3	Last Update Date
c1value2	c2value1	c3value1	01-Apr-2023

The corresponding audit table now has two rows, displaying the latest change for the audit-enabled C1 column.

C1	C2	C3	Last Update Date
c1value1	null	null	01-Jan-2023
c1value2	null	null	01-Apr-2023

Again, two months later, you turn on auditing for C2 and C3 columns. And update the value in the C1 column.

Database table will now have these values.

C1	C2	C3	Last Update Date
c1value3	c2value1	c3value1	01-Jun-2023

The corresponding audit table now has three rows.

C1	C2	C3	Last Update Date
c1value1	null	null	01-Jan-2023
c1value2	null	null	01-Apr-2023
c1value3	c2value1	c3value1	01-Jun-2023

Although the C2 and C3 columns were last updated on 1 April 2023, the audit table shows these columns are updated on 1 June 2023. The audit table is added with the snapshot of the row, every time an update is made for the audit-enabled columns. But here, the update for columns C2 and C3 is that they were enabled for auditing. Going forward, the audit table will be updated for C2 and C3 columns only if there’s any change in the values in these two columns.