The DefiningQuery element in store schema definition language (SSDL) defines a query that maps to data-store views through client-side projection within the Entity Data Model (EDM). Such mappings are read-only. Without client-side projection, users map all store-view columns and provide a dummy update customization.

A narrow projection of system views is used to generate a default EDM. The defining query is read-only. Entity Data Model Tools use mapping artifacts to start workflow.

The following SSDL syntax shows the declaration of an EntitySet followed by the DefiningQuery element that contains a query used to retrieve the view.

<Schema> 
    <EntitySet Name="Tables" EntityType="Self.STable"> 
        <DefiningQuery> 
          SELECT  TABLE_CATALOG, 
                  'test' as TABLE_SCHEMA, 
                  TABLE_NAME 
          FROM    INFORMATION_SCHEMA.TABLES
        </DefiningQuery> 
    </EntitySet> 
</Schema>

The support for stored procedures in the ADO.NET Entity Framework can be used to enable read-write scenarios over arbitrary views that the user knows how to update. Either a store-view or an Entity SQL view can be used as the base table for retrieving data and for change processing by stored procedures.

See Also