Archiving data

[jamjawaller]

I have a database that runs data reports against employee's salaries. I have a table of all employees with their salaries from which other data is calculated in a report. If an employee gets a raise...I change the salary in the employee table...but then all my calculations change to reflect the new salary during the past year. How do I prevent this so I can show the old calculations before the salary change?????

Thanks in advance.

JAM