How can I limit selections in a listbox to only and always have exactly two selections?

[lain_]

Exactly as the question above states. For more information, the values in the list box are years and the purpose is to do a calculation between two years so I always need exactly two years selected in the listbox.

[chrismarlow]

Hi,

If you can change the data model then possibly you could try adding a new table/field that gives combinations of the years that then links through to the dates, you could then use 'Always One Selected Value' on that field, something like the below;

Otherwise I think you might have to try to do something on the field event triggers possibly involving using macros ... which I think would be clunky.

Cheers,

Chris.

[lain_]

Could you link your qvw on how to do that? Thank you.

[chrismarlow]

I've been very lazy and hard coded the date pairs. You could do it dynamically, would depend how many date pairs you have & if you would want them to change (without going & adding in).

[lain_]

How would it be done dynamically?

[chrismarlow · Accepted solution]

In the toy app I sent, replace the hard coding with something like;

data_dates_temp:
Load distinct
	Date as D1
Resident data_date;

join (data_dates_temp)
Load 
	D1 AS D2
Resident data_dates_temp;

load 
	D2&'/'&Right(D1,2) AS Dates,
	D2 AS Date
Resident data_dates_temp
Where D1>D2;

load 
	D1&'/'&Right(D2,2) AS Dates,
	D2 AS Date
Resident data_dates_temp
Where D2>D1;

DROP Table data_dates_temp;