Overview of ODATA in SAP

 

Data Model is design of Data. How related data is put together in data collection called Entities and how entities relate to each other.

Entity Types

    * Entity Type or Entity is like a structure which can hold one data record. In ABAP programming terms, we can compare it to a work area.

    * Entity type has properties with some of the properties marked as Keys. More details on the properties like Type, Length are also defined.

Entity Sets

    * Entity Sets are collection of same entity types. Order Detail is an entity – Order details i.e. Collection of multiple order detail entities is an Entity Set. This is like a table.

    * Entity Set simply refers to Entity Type.

Association

    * Associations are relationships between two entity types. It defines the cardinality/multiplicity between the related entities.

    * In this example, Orders and Order Details Entity Sets are Associated where one Order has multiple Order Details items. The key that connects these two sets is OrderID as specified in Referential Constraint.

    * When an association is created between Principal Entity to Dependent Entity, a Navigation Property is also created from Principal Entity to Dependent Entity.

    * In this example, a navigation property is created for Entity Type Orders. This allows us to navigate from Orders to Order Details Entity Set.

    * Association / Navigation Properties will help us in getting related data. For example getting Order Details for a specific Order. You can easily imagine application which shows Orders first and when users select a order, display the item details.

Association Sets

    * Entity Types are collected into Entity Sets. Similarly, Association Collection is called Association Sets.


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