topic Re: FULL OUTER JOIN with ABAP CDS in Application Development and Automation Discussions

FULL OUTER JOIN with ABAP CDS

former_member240882 — Wed, 22 Nov 2017 06:22:33 GMT

How can I implement a FULL OUTER JOIN in ABAP CDS ?

Re: FULL OUTER JOIN with ABAP CDS

Sathya_Gunasekaran — Wed, 22 Nov 2017 11:45:07 GMT

Have you tried UNION ?

Re: FULL OUTER JOIN with ABAP CDS

former_member240882 — Wed, 22 Nov 2017 14:32:41 GMT

I was thinking about

LEFT OUTER JOIN

UNION

RIGHT OUTER JOIN

but I am not sure if this is the best way to do it.

Re: FULL OUTER JOIN with ABAP CDS

retired_member — Wed, 22 Nov 2017 15:20:30 GMT

CROSS JOIN?

https://help.sap.com/http.svc/rc/abapdocu_752_index_htm/7.52/en-US/index.htm?file=abencds_f1_joined_data_source.htm

I know it is a difference, but maybe it is what you need?

Re: FULL OUTER JOIN with ABAP CDS

Sathya_Gunasekaran — Thu, 23 Nov 2017 12:01:01 GMT

You may want to use 'DISTINCT' to eliminate duplicates!

Re: FULL OUTER JOIN with ABAP CDS

former_member240882 — Thu, 23 Nov 2017 16:26:04 GMT

Thank you for the suggestion.

While a CROSS JOIN does all combinations of the LHS and RHS, a FULL OUTER JOIN is a UNION of LEFT OUTER and RIGHT OUTER JOINS. I decided to go with the later solution. May not be the best way to do it but I think this is something that one would expect out of CDS views in ABAP given that it is available in HANA.

I can't think of a way to use a CROSS JOIN in lieu of a FULL OUTER JOIN.

Just for the enlightenment of readers, here is a note on FULL OUTER JOIN available in HANA

https://blogs.sap.com/2014/05/25/all-about-joins-using-sql-in-hana/