Cross Database Joins - Tableau in Two Minutes

In this video, we walk through cross database joins. These are a way of creating joins or unions on mulitple data sources at the same time. We'll join two different Excel files (although you can do the same with two different databases). You can use the smae join technique for a database and an Excel file, a database and a CSV, an Excel file and a CSV, etc.
We cover:
- How to set up your first connection.
- How to add a second connection.
- How to look at the tables in each connection.
- How to define the join.
- How to identify which columns are from which source.

[@DarbazDara]

you saved weeks of work in your 2 minutes, thank you

[@user-kp6jh6gi5z]

what needs to be the condition to go for cross data base joins?common column from both the data sources..would that be enough?

[@nishchayhanda5990]

how would you union these multiple data sources in such a case? thank you.

[@anirudh021]

whats the difference between normal join and cross database joins ?

[@penguinanalytics1984]

Hi Anirudh, regular joins are between to sheets or tables from the same source. Cross database joins are between two different sources - for example a database table and an Excel sheet, or a CSV and a database table.

[@gavinjenkins899]

It's not actually joining though? it makes weird duplicate columns, as you can see in the video, there's not just an F1, there's an "F1" and then also a "F1(monthly1)", that's not what a join is. it's more like it's doing some kind of "sideways union"
Sure I could just ignore that column, but this makes a lot of visualizations impossible. Like for example, what if I want to make a line graph with data from the first database in red and data from the second database in blue?
I would want to have not two different columns "field_fromDB1" and "field_fromDB2", instead I'd want "Database" with values 1 or 2 in it, and "field_I_want_to_graph" with data from both, distinguished by the "Database" column. Then i could mark color with Database, and draw the lines with "field_I_want_to_graph"
But due to this annoying not-actually-a-join duplicating columns thing, I can't figure out how to do that. Do you know how? The Tableau help documents don't show it like this they show a real join with only one of each column