According to the SAP HANA Developer Guide, XSODATA supports the following HTTP commands to define the operations on the resources:

• DGET: Retrieves a single entity or a collection of entities from the data source.
• DPUT: Updates an existing entity in the data source.
• POST: Creates a new entity in the data source.
• DELETE: Deletes an existing entity from the data source.

The READ and INSERT commands are not valid HTTP commands for XSODATA. They are keywords that can be used in the service definition file (.xsodata) to specify the access mode for each entity set. References: SAP HANA Developer Guide, Chapter 6, Section 6.4.2, page 2111

To produce sales value for the month using sales order line items (sales price per item x quantity sold), you can use a calculated column of a calculation view that performs the multiplication of the two columns and applies a transparent filter and a non-equijoin to restrict the data to the desired month. A transparent filter is a filter condition that is applied to the data source of a view node and is propagated to the subsequent nodes. A non-equijoin is a join condition that uses operators other than equality, such as greater than, less than, or between. For example, you can use a transparent filter to filter the sales order line items by the month of the order date, and then use a non-equijoin to join the sales order line items with the sales price table by the order date and the valid from and valid to dates of the sales price. References: Transparent Filters, Non-Equijoins, Create Calculated Columns.

Associations are used in the persistence model for SAP HANA extended application services, advanced model (XS advanced) to define the multiplicity and key of an entity relation. An entity relation is a logical connection between two entities, such as one-to-one, one-to-many, or many-to-many. Multiplicity specifies how many instances of one entity can be related to one instance of another entity. Key specifies which attributes of the related entities are used to identify and join the instances. Associations are defined using the Core Data Services (CDS) language, which is a declarative language for modeling data structures and services. Associations are part of the CDS entity definition, and they can be used to navigate from one entity to another, and to filter, aggregate, or project data from the target entity12.

The other options are not correct because they are not the purposes of using associations in the persistence model for XS advanced. Associations do not enforce database-level constraints, such as primary keys, foreign keys, or check constraints. These constraints are defined separately using the CDS annotations or the SQL DDL statements. Associations do not define the relationships between contexts and views, which are different types of CDS artifacts. A context is a namespace for grouping related CDS artifacts, such as entities, views, types, or associations. A view is a CDS artifact that defines a data model based on one or more entities or other views, and applies filters, joins, aggregations, or other operations on the data. Associations do not set relationships between multiple contexts, which are independent from each other and do not have any logical connection. References:

• SAP HANA Platform, SAP HANA Modeling Guide for SAP HANA Web Workbench, Core Data Services
• SAP HANA Platform, SAP HANA Developer Guide for SAP HANA Web IDE, Developing Database Modules, Developing Core Data Services Models, Defining Associations