Joining tables in Tableau - Step-by-Step Guide

Introduction

Joining tables in Tableau lets you combine data from two or more tables into one view. This helps you analyze related information together without manually merging data outside Tableau.

When you have customer details in one table and their orders in another, and want to see all info together.

When sales data is split by year in separate tables and you want a combined report.

When product info is in one table and inventory counts in another, and you want to analyze stock by product.

When you want to compare data from two different sources that share a common field like employee ID.

When you need to enrich your main data with additional details from a lookup table.

Steps

Step 1: Open Tableau and connect to your data source

- Data Source page

You see the list of available tables from your data source

Step 2: Drag the first table onto the canvas

- Data Source page

The first table appears as a box on the canvas

Step 3: Drag the second table next to the first table on the canvas

- Data Source page

Tableau prompts you to create a join between the two tables

Step 4: Click the join icon between the two tables

- Data Source page

Join configuration panel opens showing join type and fields

Step 5: Select the join type (Inner, Left, Right, or Full Outer)

- Join configuration panel

The join type changes and Tableau previews the joined data accordingly

💡 Inner join keeps only matching rows; Left join keeps all from the first table

Step 6: Choose the fields from each table to join on by clicking the join clauses

- Join configuration panel

The join clause updates and Tableau shows matching rows based on selected fields

Step 7: Review the data preview to confirm the join works as expected

- Data Source page

You see combined rows from both tables based on the join conditions

Before vs After

Before

Two separate tables: Customers with 100 rows, Orders with 500 rows, no combined view

After

One joined table showing customer info matched with their orders, total rows depend on join type

Settings Reference

Join Type

📍 Join configuration panel on Data Source page

Determines which rows from each table appear in the joined result

Default: Inner

Join Clauses

📍 Join configuration panel on Data Source page

Defines the fields used to match rows between tables

Default: None

Common Mistakes

Using the wrong join type like Inner join when you need all records from one table

This excludes unmatched rows, causing missing data in analysis

Choose Left or Right join to keep all rows from the main table as needed

Joining on fields with different data types or mismatched values

No rows match, resulting in empty or incorrect joined data

Ensure join fields have the same data type and clean matching values

Summary

Joining tables in Tableau combines related data for richer analysis.

Choose the correct join type to control which rows appear in the result.

Always verify join fields match in type and content to avoid empty joins.