xls cascading lookup based on pivot table style datasource?

Question

Assuming dataset looks like

Country Region  Product
UK  North   fdhlw46
UK  North   fdhlw47
UK  North   fdhlw48
UK  North   fdhlw49
UK  North   fdhlw50
UK  South   fdhlw51
UK  South   fdhlw52
UK  South   fdhlw53
UK  South   fdhlw54
UK  South   fdhlw55
UK  South   fdhlw56
UK  South   fdhlw57
UK  West    fdhlw58
UK  West    fdhlw59
UK  West    fdhlw60
UK  London  fdhlw61
UK  London  fdhlw62
USA New York    fdhlw63
USA New York    fdhlw64
USA New York    fdhlw65
USA New York    fdhlw66
USA Chicago fdhlw67
USA Chicago fdhlw68
USA Chicago fdhlw69
USA Chicago fdhlw70
USA LA  fdhlw71
USA LA  fdhlw72
USA LA  fdhlw73
USA LA  fdhlw74
USA LA  fdhlw75

How can I get cascading dropdowns/picklists in excel where the users selects, the country, which then narrows down to region and finally product?

So far all I have is a range called 'country' which I can then "data - validation - source: = country", but this only gives me the first value, and it doesn't strip duplicates

Answer 1

http://www.contextures.com/xlDataVal13.html

This approach does mean defining a unique set of values for each grouping, but this is trivial.

Thanks for the other ideas.

Answer 2

Select the range then Data -> Filter -> Autofilter. Does that achieve what you're looking for?

Answer 3

I think you want to use the INDIRECT function to lookup the value of a cell, rather than define a lookup range directly in the data validation. Have a look at this page which explains it fairly well.

Be warned though that multiple cascading validations like this have particular problems of their own. Chiefly, if you make a second (or third etc.) selection, then go back and edit the first selection, there is no automatic flag to say that the selection may now be invalid. For example, if you have the following:

Type        Detail
Fruit       Apple

...and then change the first column:

Type        Detail
Vegetable   Apple

...then you may now have a problem. Finding such inconsistencies can be very hard, or requires some code to highlight/fix. The DDoE blog shows one method to highlight such errors using conditional formatting, but this is very calculation intensive and doesn't scale well.

Be aware that multiple lookups of this nature can bring a workbook to its knees if used liberally, even without using conditional formatting.

All in all, for a small project where data entry is tightly controlled this is a flexible method of cascading drop down lists, but if you have little control over the users, or if the data collected will grow past a few hundreds lines then you'll probably want to look at validating the validation (!) using VBA, or just going the whole hog and forcing entry through a userform, which is by far the best option.

Edit: Example workbook

Edit again: If the data absolutely has to stay the way it is, then an advanced filter which creates the named ranges used in the validation would be required. At this level of complexity though you'd surely be better off just using a form for data entry.