Hi!
Like this:
Select Sum(ORDERS.UNITS) as UNITS_PURCH, Sum(RETURN.UNITS) as UNITS_RET, Sum Sum(ORDERS.UNITS) - Sum(RETURN.UNITS) as NET_UNITS
Of course, if you plan on using this in a report then it might be quicker to do the calc in a text box. Then you could us UNITS_PURCH and UNITS_RET.
hth
Jeff Bridgham
Purdue University
Graduate School
Data Analyst