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Unexpected Results When Using LEFT() Function with non-English Strings


Published: 18 Feb 2018
Last Modified Date: 19 Feb 2018

Issue

After upgrading Tableau from 10.0 to 10.4, the function LEFT() does not work properly with non-English strings when connecting to MySQL.

For example in Chinese, when [系统二级部门]='中拓二部', LEFT([系统二级部门],2)='中拓' returns False. The correct result would be True.

Environment

  • Tableau Desktop 10.4.0
  • MySQL

Resolution

Upgrade to Tableau Desktop 10.5.1 or 10.4.4. For more information, see Upgrading Tableau Desktop in Tableau Help.

 

Cause

An optimization was introduced to rewrite some LEFT() functions using 'startswith' but it doesn't account for different sized characters. Additionally, this behavior is related to a known issue (ID: 718104) which has been fixed in a recent release of Tableau Desktop. 
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