You don’t.
Tableau Desktop will allow you to union multiple tables from the same database or even multiple .csv files, but you can’t union a table from SQL Server A with a tableau from SQL Server B.
So what do you do?
That’s where Tableau Software’s new product Tableau Prep comes in handy. This might be the single biggest limitation from Tableau Desktop that Prep solves.
In Tableau Desktop you can perform a join between two tables from different data sources but not a union:
Tableau Prep makes this process incredibly simple with the use of a single union tool:
Want to learn more about what Tableau Prep can do for you? Check out our Tableau Prep Foundations Workshop.