I have a data set with a field called email_name. The values are obscure and don't mean anything to anyone on the business end, so I'd like to do some lookups using something like an Excel file or a SharePoint list that the business users maintain. For instance, I might have email_name value "C12345_em_sep18_othernonsense", but the business wants to categorize anything containing "C12345" as "Email Campaign A". Right now we have a calculated field that has a case statement with a ton of contains() functions for things like this. Long term it's not a sustainable solution. If I can look up values with some dynamic logic I could easily mark anything containing "C12345" as "Email Campaign A". There are sometimes hundreds, even thousands of different records that might fall into a single category. Can anyone offer any suggestions, aside from a very basic join such as email_name = some_lookup_file_field that will allow me to do this in a way external to Tableau Desktop?