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Error Saving View When Joining to Same Table Multiple Times

I'm trying to create a derived view using the Denodo Design Studio web app. Let's say I have two views: DERIVED_VIEW and BASE_VIEW. These two views have a one-to-many relationship (DV-to-BV). I'm trying to create a new derived view which uses DV as the left side of three left outer joins to BV in order to get the values I need. The pseudo-code looks like this: ``` select DV.id, BV1.code, BV2.code, BV3.code from DERIVED_VIEW as DV left outer join BASE_VIEW as BV1 on BV1.id = DV.id and BV1.type = 'A' left outer join BASE_VIEW as BV2 on BV2.id = DV.id and BV2.type = 'B' left outer join BASE_VIEW as BV3 on BV3.id = DV.id and BV3.type = 'C' ``` If I create the join to BV1 and save the new derived view it saves with no problem. As soon as I add the second join and try to save I get the error message: 'Error saving view: ' - with no additional message. Another strange thing is that when I try to delete the new join the app crashes and I have to log back into Design Studio (message: 'An internal error has occurred. Please contact your system administrator.'). I'm not an admin so I don't have access to the logs. I've gone over the VQL syntax and the output tab multiple times and I don't see any errors. I've signed out and back into Design Studio but nothing works. Can anyone help me with this?
user
18-08-2023 06:41:56 -0400
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2 Answers

Hi, I think that it is a known issue that will be corrected in a future update. I’d try to create the join view via VQL shell or Virtual DataPort Administration Tool. To create it in the VQL shell you can refer to the [JOIN Operation](https://community.denodo.com/docs/html/browse/8.0/en/vdp/vql/queries_select_statement/from_clause/join_operation) section of the Virtual DataPort VQL Guide. Hope this helps!
Denodo Team
21-08-2023 04:41:43 -0400
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Denodo Team, I was able to use the workaround you suggested (VQL shell) to create and successfully execute the view script. The new view then displayed in the Explorer tab and I was able to use it from there as a foundation for further views. Thank you.
user
21-08-2023 12:03:00 -0400
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