ABAP CDS: Joins and Associations

[former_member185171]

Hi All,

we are beginning development of CDS-views and trying to find our way in it.

We imported some CDS's for SLCM, and need some guidelines on the use of joins and associations:

as select distinct from PiqCds_OrgUnitPrograms ( p_idate : $parameters.p_date, p_lang : $parameters.p_lang) as org

...

inner join PiqCds_ProgramStudy ( p_idate : $parameters.p_date, p_lang : $parameters.p_lang )

as prog

on org.ProgramOfStudy = prog.ProgramOfStudy and org.ActivePlanVersion = prog.ActivePlanVersion

...

inner join dd07t

as text1

on text1.domname = 'PIQHS_STATE' and text1.ddlanguage = $parameters.p_lang and text1.domvalue_l = reg.prs_state

..

association [0..*] to PiqCdsAcademicYear as _AcademicYear on _AcademicYear.AcademicYear = reg.ayear

association [0..*] to PiqCdsAcademicSession as _AcademicSession on _AcademicSession.AcademicSession = reg.perid

...

Can anyone tell me why sometimes JOINs are used and sometimes ASSOCIATIONs?

Are there some guidelines when you should use one or the other?

Thanks for helping.

Kris

[waldemar_schakiel]

Hello Kris,

associations should be prefered in CDS because defining associations is a more alegant way to code reusable joins. Associations can be adressed inside the view using path expressions and can be published for usage in other views.

Greetings

Waldemar