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Linking Tables Using One-to-Many Relationships


Published: 04 Apr 2014
Last Modified Date: 06 Sep 2019

Question

How to create one-to-many relationships in Tableau Desktop.

Environment

Tableau Desktop

Answer

Joining tables causes duplication of data. When joining multiple large tables, the data duplication can slow performance and increase the difficulty of manipulating the data.

The following instructions can be reviewed in the attached workbook.

Option 1: Aggregate Extracts

  1. In the Data pane, right-click (Product Name) and select Hide to hide the duplicating field.
  2. Right-click Sales and select Default Properties > Aggregation > MIN.
  3. Right-click data connection and select Extract Data.
  4. Check the box Aggregate data for visible dimensions.
  5. Click Extract.
For additional information about this topic, see in Data Aggregation in Tableau

Option 2: Data Blending

  1. Connect to each table separately.
  2. Establish a relationship at the level needed to blend and not at the duplicating field level: Data > Edit Relationships.
  3. Build visualization while omitting the lowest level of detail that is causing the duplication.
For additional information about this topic, see Blend Your Data in Tableau Help. 

Option 3: Custom SQL

  1. Write a sub query that contains measure to sum and the field that is one step higher than the duplicating field.
  2. GROUP BY that field.
  3. Insert that new measure into the select statement.
  4. Build visualization with the new measure instead of the old one.
For additional information about this topic, see Connect to a Custom SQL Query in Tableau Help. 

 

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