Data blending is different from joins in that joins are done at a row level, but data blending is done at an aggregate level. So you wouldn't be able to compare the dates from rows of Something and the dates of rows from Dim_Date. However, there are ways to constrain blends using filters and calculated filters. Much would depend on your view and the level of aggregation. Do you have a specific case? Would you be able to share some data or, even better, a packaged workbook (.twbx)?
Any idea like how to we do conditional blending in tableau?
I have 3 data sources which I need to blend on some specific condition.
Any ideas or help would be appreciated.