构建数据库以跟踪数据的某些更改

Question

I have a SQL Server 2008 R2 database in which I need to track certain changes made to the data. So far all of my research has brought up ways to do quite complex tracking of every change made, but my case is somewhat more specific and, I think, simpler as I only need to track a change until it is approved (by an administrator).

So far the only way I can think of to do this is, for each affected table, to create a pending_changes table which tracks the type of change (ie INSERT , UPDATE or DELETE ), the primary key, the column name, and, where applicable, the value or values to be changed.

Then when a change is approved, a SQL statement can be generated from this to write the change to the main table. This feels like a very clumsy way of doing it though, and it will be difficult to query this (eg to produce a list of old vs new values).

This is a very small database (< 1000000 rows) with only about 5 users, so performance is not an issue.

EDIT: The purpose of tracking changes is that they need to be approved before they can be written to the database. The data is mostly scientific with legal implications, so changes proposed by a user (in this case a client) need to be checked by an expert before they can be approved. Once they have been approved, we don't need to know the old values any more. All changes, including DELETE statements need this approval. INSERT and UPDATE could be dealt with by creating a similar table which holds the changed data, but I'm not sure how to deal with deletions. I also want to avoid too many extra tables because there are several base tables I need to track, and I am worried about the added complexity.

Answer 1

You can use an "Instead of" trigger.

(not tested)

CREATE TRIGGER IO_Trig_INS_Employee ON Employee
INSTEAD OF INSERT
AS
BEGIN
  insert pending_employee
    select * from inserted
end

http://msdn.microsoft.com/en-us/library/ms175521(v=SQL.105).aspx

The MERGE keyword can help with applying the changes. You may have to drop the trigger before making the change though.

http://msdn.microsoft.com/en-us/library/bb510625.aspx

Have you considered handling this in the application? Something like an approval workflow in Sharepoint might be better suited.

Answer 2

Are you tracking the changes with the intent of preventing undesirable ones before they are made, or to be able to review/revert the values back after they are made?

If you are okay with allowing the user to make the insert/update/delete and then have an admin approve it, consider using OUTPUT INTO clause. There is a great example in the section labeled "C. Using OUTPUT INTO with an UPDATE statement" at this page: http://msdn.microsoft.com/en-us/library/ms177564.aspx

USE AdventureWorks2012;
GO
DECLARE @MyTableVar table(
    EmpID int NOT NULL,
    OldVacationHours int,
    NewVacationHours int,
    ModifiedDate datetime);
UPDATE TOP (10) HumanResources.Employee
SET VacationHours = VacationHours * 1.25,
    ModifiedDate = GETDATE() 
OUTPUT inserted.BusinessEntityID,
       deleted.VacationHours,
       inserted.VacationHours,
       inserted.ModifiedDate
INTO @MyTableVar;
--Display the result set of the table variable.
SELECT EmpID, OldVacationHours, NewVacationHours, ModifiedDate
FROM @MyTableVar;
GO
--Display the result set of the table.
SELECT TOP (10) BusinessEntityID, VacationHours, ModifiedDate
FROM HumanResources.Employee;
GO

As you can see, this will allow you to record both the "before" and "after" values of each column.