In other words you want to be able to reproduce an invoice (for example) for a period that may be a week, a month or a year ago and have it pull the correct hourly wage from your history table?
Are you also putting a termination date on your wage. For instance if your employee 1 has had 2 wage increases does your table look something like:
Code:
tblWage
EmployeeNumber Wage DateEffective DateTerminated
1 10.00 1/1/2009 9/30/2009
1 10.50 10/1/2009 4/5/2012
1 11.50 4/6/2012
where the most recent wage is the one with the open termination date?