Date fields are only treated as dimensions by default, but you can certainly use a date as measure instead. Measures are aggregated in Tableau, so you would normally compute the max (i.e. latest) date value, or the min (i.e. earliest) data value, or perhaps the count or distinct count of a data field.
Tableau will submit a separate query to each data source and return the aggregate of the results from the secondary data source(s). The results from the secondary data source are aggregated at the level of the common fields available between the data sources. This means we can only slice each measure (numeric field) by the common fields.
I want to do the similar but with pie chart. I have simple data.1. Metric Data, Current Value, MTD (calculated), YTD (calculated) values which needs to be shown as green/red based on three measure Lo, Hi, Metric Value, if the Current Value > Hi or Current Value<Lo need to show it as red other case I need to green. same condition for MTD and YTD.