I have pivoted the data so the different columns (like Under Management, On Therapy, and Case Open) will come as a rows and changed the data type for each of these columns to date instead of string.
Please find the attached solution, hope this helps.
Sample Tableau_1.twbx 44.6 KB
Kumar's answer is good.
The important parts are - he first pivoted the data,
(the data prep stage is SO important, everything will be easier if your data is the right shape to start with)
and changed the data types.
Your dates were coming through as numbers, this can be fixed when you first link to the data source
more here >> Data Types
(that's also why the Patient ID has decimal places... although they are numbers, I suspect you want them as string)
If anything isn't clear please do ask, these are really important basic concepts.
This is fantastic. I didn't realize this was an option in Tableau. Thank you so much!