Calculated control does not recalc automatically

Question

Firstly, a bit about my setup.

I have a primitive database of three tables:

A. Table that lists various locations: [location_code], [location_name]

B. Table that describes items: [item_code], [item_name], [item_price]

and finally a table that ties the roo^H^H^H whole database together

C. Table says which items are stored at each locations and in what quantities: [location_code], [item_code], [item_quantity]. This table can have multiple entries with the same [location_code], since different items can be stored at the same location. Basically, this is a schoolbook implementation of one-to-many relationship from locations to items, with a extra attribute (quantity) attached to each location-item link.

Now, all I need to do is to create a form that would list all items stored at certain location. This is a basic use-case for "subform" feature in Access. The main form simply navigates through different locations, while the subform lists the items.

I use

SELECT C.location_code, B.item_name, B.item_code, B.item_price, C.item_quantity 
FROM B INNER JOIN C ON B.item_code=C.item_code

as a record source for the subform. The main form is linked to subform by [location_code]. The subform is set up with list layout (not table layout), i.e. each database field is given its own control element.

So far everything works perfectly. I select the location in the main form, and the subform gives me a list of editable [item_name]-[item_price]-[item_quantity] triplets for the current location.

As the next step, I want to add a calculated control to each of the above triplets. I want to know the total price for each kind of item (i.e. simply the [item_price] * [item_quantity] in each line). Easy, I add a calculated control to the "repeatable" area of the subform and specify

= [item_price] * [item_quantity]

as the formula for the value. Again, everything works perfectly. Now instead of the above triplets, my list has four entries per line: [item_name]-[item_price]-[item_quantity]-[total_item_price]. And, what is important, when I edit [item_price] or [item_quantity], the [total_item_price] gets automatically reevaluated once I finish editing.

And as the final step, I want to add another calculated control that would display the total price of all items stored at the current location (let's call it "grand total"). A also place that control into the subform (into the "footnote" area this time) and specify the following formula as its value

= SUM([item_price] * [item_quantity])

Now, this works. The total value is calculated correctly each time I change the location in the main form. Also, when I change [item_price] for any item at the current location, the grand total is also updated automatically. However, when I change [item_quantity], the grand total does not update (???). Hitting F9 will make it update. Changing the current location back and forth will update it. But, unfortunately, a mere change to [item_quantity] does not trigger an automatic update.

Does anyone know, what could be wrong here? Why do changes in [item_price] trigger the automatic update of the grand total, while changes in [item_quantity] do not? Intuitively, these fields seem to have the same status (except that the former comes from table B, while the latter comes from table C). Why is the behavior different? How do I make it update automatically?

Answer 1

In your subform's after update event, explicitly recalculate the total price control.

Me.txtTotalPrice.Requery

Answer 2

If you tab through the record and advance to the next record does it still not update. I am thinking that the price is the last field in tab order so when you change it, you tab on to the next record and the change is committed. If I am right then when you edit the quantity, your tab advances you to the price field which is still in the current record so the change is not committed to the table yet. If you advance further through, that should complete the processing.