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"1" dependent "Orders"("CustomerID") multiplicity "*";
}
The example above says that it is possible to navigate from Customers over the association
Customer_Order via the NavigationProperty named "HisOrders".
The right association end is determined automatically by the entity set name. But if both ends are bound to the
same entity, it is necessary to specify the starting end for the navigation. This is done by specifying either from
principal or from dependent which refer to the principal and dependent ends in the association.
Service definition: sample.odata:assocnavself.xsodata
service {
"sample.odata:customer.hdbtable" as "Customers"
navigates ("Customer_Orders" as "HisOrders","Customer_Recruit" as
"Recruit" from principal);
"sample.odata:order.hdbtable" as "Orders";
association "Customer_Orders" principal "Customers"("ID") multiplicity
"1" dependent "Orders"("CustomerID") multiplicity "*";
association "Customer_Recruit" principal "Customers"("ID")
multiplicity "1" dependent "Customers"("RecruitID") multiplicity "*";
}
In both cases a NavigationProperty is added to the EntityType.
http://localhost:8002/sample/odata/assocnavself.xsodata/$metadata
OData Aggregation
The results of aggregations on columns change dynamically depending on the grouping conditions. This means
that aggregation cannot be performed in SQL views; it needs to be specified in the OData service definition itself.
Depending on the type of object to expose, you need to explicitly specify the columns to aggregate and the
function to use or derived them from metadata in the database.
In general, aggregations do not have consequences for the metadata document. It just effects the semantics of
the concerning properties during runtime. The grouping condition for the aggregation contain all selected nonaggregated
properties. Furthermore, aggregated columns cannot be used in $filter, and aggregation is only
possible with generated keys.
SAP HANA Developer Guide
Defining Web-based Data Access
P U B L I C
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