refering to a field that is not in a form

[shutzy]

i would like to know if it is possible to refer to a field even tho it is not in a form

ie

strSql = "UPDATE tblItems " & _
 "SET StockQTY = ([StockQTY]+1) " & _
 "WHERE ItemsID = " & [ItemsID] & ""

the [ItemsID] is actually on the form as a txt box. but i dont really need it there for any other purpose other than the vba above.

in the form i have a field that is in the form as a txt box that has a relationship to the ItemsID. i have attached a image of the relationship.

the field that is in the form is tblOrdersItems.OrdersItemsID and i also have tblItems.Items. so rather than adding another meaningless txt box to the form(ItemsID) i would like to be able to use the relationships to get the correct ItemID

thanks for any help