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Error "ORA-00918: column ambiguously defined" Occurs when Tables in a Join are Renamed Similarly


Published: 07 Apr 2022
Last Modified Date: 07 Apr 2022

Issue

Error "ORA-00918: column ambiguously defined" occurs when 2 tables with similar names are joined as shown below.

User-added image

Environment

  • Tableau Desktop
  • Oracle

Resolution

Workaround

Use different table names less than 30 characters long

Cause

This is due to the Oracle (12.1 and earlier) design limitation on object name length. 
Part of the table names that are longer than 30 characters are truncated and end up as being ambiguous. 
 
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