Subform query troubles

[Turbo910]

Hey guys once again i need your expert advice please.

I have a form (frmEquipmentHire) with a subform (TESTSUB). in the subform is the prodcut ID and name, Quantity on hand, the Quantity order, and the price.
Basically i need an update query to update the quantity on hand field in the back tables.
the calculation would be quantity on hand - order quantity and i have tried this but had no luck. I think becaue it is in a subform it needs different syntax and ive tried some things but still no luck.

This is for my ICT coursework so a solution asap would be great even if its just a code that i can copy and paste please.

Thanks in advance

 

[KenHigg]

If this is course work why don't you ask the instructor for help, asap?

 

[JamesMcS]

Can't you just use docmd.runsql to run an update query, in the on click of your parent form? You can refer to the values in your QOH and Qty_Ordered like this:

Form![Mainformname]![Subformname].form![ControlName]