[MDEV-11986] CONNECT ODBC Bug: Engine Converts LEFT JOIN into INNER JOIN Created: 2017-02-03  Updated: 2017-02-03  Resolved: 2017-02-03

Status: Closed
Project: MariaDB Server
Component/s: Storage Engine - Connect
Affects Version/s: 10.1.21
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Juan Telleria Assignee: Olivier Bertrand
Resolution: Not a Bug Votes: 0
Labels: None
Environment:

Windows


 Description   

I just realized about a bug, I do not know if it is because of the CONNECT ODBC Engine or MariaDB Server itself:

When I do a query such as:

SELECT
 
     *
 
FROM
 
     t_name_Local_Server AS A
 
     LEFT JOIN t_Name_Remote_Server AS B
 
          ON A.Join_Column_Name = B.Join_Column_Name

MariaDB returns a Result Set which performs an INNER JOIN, not a LEFT JOIN. That is, it returns a result set which contains only those rows which are not null in Table aliased as B (t_Name_Remote_Server).

 Comments   
Comment by Olivier Bertrand [ 2017-02-03 ]

This is logical. In this query t_Name_Remote_Server is not a real table but the result set retrieved from the remote server. SQL result sets do not contain null rows. This explains that.

Ok to add this information in the documentation.

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