Question

I have a situation where I want to associate multiple values from one table with a value from another. I’ve got my data structured with a many-to-many join table in between, and I’m trying to manage the membership in the join table.

This question is about the UI portion of the process. I think that what I want to do is to present the user with a multi-select List Box control on a form that holds the ID of TableA constant (and, incidentally, hidden). The List would be populated with all the (fairly short list of) rows from TableB (descriptions displayed, IDs in hidden column). On load, I’d select those rows of the list that participate in the M-M join. The user could select additions and/or deselect removals.

What I’m not sure about is how to tell whether or not any given row is selected. I know about the IsSelected collection–if I were just adding, I’d walk that with For Each, but I need to remove any that have been deselected, and I need to not re-add any that already exist. What I’m thinking at this point is walking the whole list, testing each selected value & inserting it if not already present, and testing each un-selected value for possible deletion (hmmm–that’s starting to sound needlessly complex….).

What I started out to ask was “how do I tell if row(x) is selected?” I’d still like the answer to that, but I’m open to other suggestions for managing the base problem, as well

Answer 1

In seems that you have a list that you are using to create the selected items. After the user has updated the list box, you can compare .ItemsSelected to the rows of the list that participate in the M-M join. Missing items can be deleted and additional items can be added. A few very rough notes:

For Each itm In Me.AList.ItemsSelected
    rsJoinList.Find "ID=" & Me.AList.Column(0, itm)

    If rsJoinList.NoMatch Then
        'To be added
    Else
        'To be deleted
    End If
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