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ObjectQuery<T>.Select(String, ObjectParameter[]) Method

  • Reference

Definition

Namespace:
System.Data.Objects
Assembly:
System.Data.Entity.dll

Limits the query results to only the properties that are defined in the specified projection.

public:
 System::Data::Objects::ObjectQuery<System::Data::Common::DbDataRecord ^> ^ Select(System::String ^ projection, ... cli::array <System::Data::Objects::ObjectParameter ^> ^ parameters);
public System.Data.Objects.ObjectQuery<System.Data.Common.DbDataRecord> Select (string projection, params System.Data.Objects.ObjectParameter[] parameters);
member this.Select : string * System.Data.Objects.ObjectParameter[] -> System.Data.Objects.ObjectQuery<System.Data.Common.DbDataRecord>
Public Function Select (projection As String, ParamArray parameters As ObjectParameter()) As ObjectQuery(Of DbDataRecord)

Parameters

projection
String

The list of selected properties that defines the projection.

parameters
ObjectParameter[]

Zero or more parameters that are used in this method.

Returns

ObjectQuery<DbDataRecord>

A new ObjectQuery<T> instance of type DbDataRecord that is equivalent to the original instance with SELECT applied.

Exceptions

ArgumentNullException

projection is null.

-or-

parameters is null.

ArgumentException

The projection is an empty string.

Examples

This example creates a new ObjectQuery<T> whose results are data records that contain the ProductID fields of the results of this query.

int productID = 900;
using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    string queryString = @"SELECT VALUE product FROM
        AdventureWorksEntities.Products AS product
        WHERE product.ProductID > @productID";

    ObjectQuery<Product> productQuery1 =
        new ObjectQuery<Product>(queryString,
            context, MergeOption.NoTracking);

    productQuery1.Parameters.Add(new ObjectParameter("productID", productID));

    ObjectQuery<DbDataRecord> productQuery2 =
        productQuery1.Select("it.ProductID");

    foreach (DbDataRecord result in productQuery2)
    {
        Console.WriteLine("{0}", result["ProductID"]);
    }
}

Remarks

Select applies the projection specified by the projection parameter. The ObjectQuery<T> returned by the Select method is always a row type of DbDataRecord. Use the SelectValue method to return values that are simple types, entity types, or complex types. For more information, see LINQ to Entities.

When a navigation property is included in the projection, the query results include a collection of nested DbDataRecord objects.

Applies to

See also