Dropdown list from database with multiple same entries

I have a Skills Exchange database:

Bob-- Guitar
Jane-- Drums
Hal-- Guitar
Sally-- Drums
Barry–Bass
Bill–Guitar
Mary–Bass

How can I populate a dropdown with a unique version:

Bass
Drums
Guitar

Thanks for your help!

Chris

When you get data from the skill app, choose the field right after and select :unique elements
Example: Do a search for users’s skill:unique elements (skill is a field in user DB)