Microsoft Access Listbox Query
I think that in this case you better do this in a form.
The problem with your qeury is that it lacks where clauses. For id 1 for example, the selects to union should be:
SELECT Valx FROM Table1 WHERE ID=1
On a form you can do this for example by setting the row source in the on current event depending on the value of ID.
And yes, the structure of your database could need an update. Wich can be done with one simple query.