Data blending can be used when the two data sources you are combining are at different levels of granularity.
Here in your case as there is no sample data i am not sure if data blend is the right approach.
did you try using regular joins instead of data blend?
to resolve aggregates did u try using ATTR function in tableau?check the below links
Thanks, Bharat. Yes we tried the ATTR function, but it yield the same "Can't be to user defined aggregate" error when we tried to execute any calculated function.
Unfortunately, the data sources are of different type. One is an excel data source and the other is an server database, so I don't think regular join is an option.
can you share a sample workbook with dummy data to figure out.
Meanwhile you can check the below links,they may help you.
- 'Can't be applied to a user defined aggregate' error query on calculation