ObjectQuery<T>::GroupBy Method (String^, String^, array<ObjectParameter^>^)
Groups the query results by the specified criteria.
Assembly: System.Data.Entity (in System.Data.Entity.dll)
public: ObjectQuery<DbDataRecord^>^ GroupBy( String^ keys, String^ projection, ... array<ObjectParameter^>^ parameters )
Parameters
- keys
-
Type:
System::String^
The key columns by which to group the results.
- projection
-
Type:
System::String^
The list of selected properties that defines the projection.
- parameters
-
Type:
array<System.Data.Objects::ObjectParameter^>^
Zero or more parameters that are used in this method.
Return Value
Type: System.Data.Objects::ObjectQuery<DbDataRecord^>^A new ObjectQuery<T> instance of type DbDataRecord that is equivalent to the original instance with GROUP BY applied.
| Exception | Condition |
|---|---|
| ArgumentNullException | The query parameter is null or an empty string. -or- The projection parameter is null or an empty string. |
GroupBy applies the projection specified by the projection parameter. This means that the ObjectQuery<T> returned by the GroupBy method is always of type DbDataRecord. For more information, see Object Queries.
This example is based on the AdventureWorks Sales Model.
This example creates a new ObjectQuery<T> object that contains the results of the existing query grouped by product name.
This example returns a set of nested data records that contain the Contact.LastName column, grouped and sorted alphabetically by the first letter of Contact.LastName.
Available since 3.5