table lookup / null field values, help!

[benjammin]

Hello!

So i have a cascading combo box with 3 choices, Site, Location and Station, this is for an inventory db.



Equipment ALWAYS is attached to a Site, sometimes to a station and occasionally to a Location. The subform is based off of the Station combo box using a macro (better to use vba?). However, if a user chooses a Site that has no Station or Location attached to it, how do I tell the macro to update the subform?! Does this make sense? Could I do an afterupdate and run some sql that will lookup the row associated with the Site and see that there is no LocationID or StationID and then run something to update the subform?

Seems a little cumbersome but instead of the cascading combo boxes i guess I could make Site a subform, Location a sub-subform and Station a sub-sub-subform with their own combo boxes...

Hopefully this isn't too ambiguous. Thanks.

[rpeare]

So you want to refresh the contents of a subform based on the main form? If your main form/subform are linked correctly you shouldn't have to force a refresh at all. Or are you saying you want the contents (visible fields) to change based on the user selected items in your combo boxes?

[benjammin]

Well the subform is based on the mainform and DOES refresh when I update my combo box that is linked (stationID). My cascading combo boxes go in order: Site, Location, Station. The problem is that some sites have equipment not attached to any station and location.

I was thinking maybe the easiest way would be to just make another form, one form edits ALL hardware at a site and another form edits only hardware attached to the station.

[rpeare]

I would think you could set up the query driving your subform to properly exclude or include items based on your combo box selections. The worst case is you could set up a secondary subform that looks only at equipment that is related to site only, or equipment where locationID is null and station is null but still matches the siteID