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How to Make a Full Outer Join in Tableau Desktop When Some Databases Do Not Support Outer Joins


Published: 21 Sep 2021
Last Modified Date: 21 Sep 2021

Question

How to make a full outer join in Tableau Desktop when your database does not support outer joins. 

Note: If a database that does not support full outer joins is added to the connection, the full outer join will not work in Tableau Desktop.

For example, when connecting to MySQL, Full Outer joins are not available.
User-added image

 

Environment

  • Tableau Desktop

Answer

As a workaround, please consider creating Custom SQL to Union left join and right join.

For example, the CustomSQL could be written as follows to make a full outer join of Table A and Table B possible.
select A.No, A.Column1, A.Column2, B.Column3
from A
     left outer join B
     on A.No = B.No
  
UNION
  
select B.No, A.Column1, A.Column2, B.Column3
from A
     right outer join B
     on A.No = B.No

 
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