Expression help UserEmail()

[AntonyCole1979]

I have 3 tables, Products, Stock In, and Stock out. I currently have a sum on the products table which looks a little like this.
Column is [Stock Level]
SUM([Related In][Qty In]) - SUM([Related Out][Qty Out]).
I need to add another level in which I need to only show stock level by UserEmail(). Both the Stock in and Stock out tables will contain UserEmail() so I need to add this somehow. hope this makes sense?

Thanks

Antony

[Steve]

SUM(SELECT([Related In][Qty In], ([Email] = USEREMAIL())))
- SUM(SELECT([Related Out][Qty Out], ([Email] = USEREMAIL())))

[AntonyCole1979]

excellent, thanks Steve!
Antony