Data Type Mismatch When Adding a Connection to an Existing Connection with a Join Using Data Types Which do Not Match

Published: 14 May 2019
Last Modified Date: 12 May 2021


When adding a cross-database join to an existing connection with a join between two tables that do not have matching data types for the join clause, an "data type mismatch" error message is received.  If the data types between the two fields are the same, the join remains valid when switching the connection to a cross-database join.


  • Tableau Desktop 2019.1 - 2020.2


Option 1

1. Upgrade to Tableau Desktop 2020.3 or later.
2. Use "Create Relationship Calculation" feature
3. Select a 'Type Conversion' function to change the data type.

Option 2

Change the data type at the data source level.


In Tableau 2020.3 and later, you can create relationships based on calculated fields, and compare fields used for relationships using operators in the relationship definition.
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