I connected Tableau desktop to the MS SQL database and used custom SQL query to select the columns that I wanted.
Select productname, price, ratings, periodDate from products
I then created an extract that is incrementally refreshed by periodDate.
Now I want to add one more column to my data called periodID.
If I rewrite my custom SQL, it will mess up with my incremental refreshed data - only the updated data in the database shows but not the previous data that I had stored in the extract.
If I create a join (new table with the new column joins the old table with all historical data), the combined table gets fully refreshed and all my old data are gone again.
Is there a way that I can tackle this?
* I am using only tableau desktop at this point.
Thanks in advance!
The modified extracts will not connect to a new extract. I believe you are looking for a solution such as the one suggested in this Idea: https://community.tableau.com/ideas/7076
Please consider voting this up if this would meet your needs.