Union your data

If a join adds columns, a union adds rows.

Unions are useful when you have two (or more) tables with an identical structure (the same columns) that you want to combine to create a unique data source.

A typical use case is when you have a dataset that contains one table per year, and you need to compare those years. To do that, you need to combine those different tables into a single data source. You can, of course, spend some time copying and pasting the data into a new table, but with Tableau and unions, you can do this in a few clicks.

Note

To create a union, the different tables must contain the same column names. Otherwise, Tableau will not consider them to be identical and will create new columns.

Let's start with an example.

Hands-on with a union example

For this example, I created an Excel file with two sheets to union.

Note

If you want to reproduce the example, you can download the Union example file from my website, https://tableau2019.ladataviz.com, in Chapter 4: Connect...