How to join tables based on Calculated Fields in Tableau

Question

In order to join one of my tables to other tables, I had to use Calculated Fields to make the field format same as others. However, when I want to join the tables, the new field name created by Calculated Fields does not appear. I know that I can export modified data, and import it again to solve the problem, but I'm interested to know if there is a simpler way to do so in Tableau?

Answer 1

You absolutely can join to a calculated field, but they make you take a few extra steps:

After you drag your source over, and the dialogue box pops up, under Data Source, you will see all of your field choices but none of your calculated fields. At the bottom of these choices is Edit Join Calculation; click on it.

A Join Calculation box pops up. Type in the name of your calculated field. Put the name in [ ]'s, or after typing a few letters, the name should pop in as an auto-fill option. Once done, click ok.

Then click on the second column and choose the corresponding field you want to use for the join. At that point, it should perform the join.

For an in-depth explanation check out Tableau Training Course details.

Comments

Thanks, it works quite well.

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does this only work in later versions of Tableau? I'm using 10.4.1 and the data source doesn't recognise either the calculated fields nor a bespoke parameter to create the join calculation.

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This feature was added to Tableau 10.2 version onwards.

You can see images like below.

Click on Add new join clause,

a

Enter [ to see created calculated fields or create a new join calculation.

You can read below doc for more information regarding join calculative fields.

https://onlinehelp.tableau.com/current/pro/desktop/en-us/joining_tables.htm#joinoncalcs

Hope it helps!

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Hey! I hope you are doing good! If @Cherukuri's answer has helped you please do upvote the answer.

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Answer 2

Calculated fields are not written back to your data source. But perhaps you could Blend, not join, on it. So currently you can not join in the data model using calculated field in Tableau. If your data is not too large, you can make the join in Tableau by using data blending. Alternatively, create a view or views with the calculated field in the source SQL database.