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

Definición

Agrupa los resultados de la consulta de acuerdo con los criterios especificados.Groups the query results by the specified criteria.

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

Parámetros

keys
String String String String

Columnas de clave por las que se deben agrupar los resultados.The key columns by which to group the results.

projection
String String String String

Lista de propiedades seleccionadas que define la proyección.The list of selected properties that defines the projection.

parameters
ObjectParameter[]

Cero o más parámetros que se usan en este método.Zero or more parameters that are used in this method.

Devoluciones

Nueva instancia de ObjectQuery<T> de tipo DbDataRecord que es equivalente a la instancia original, pero aplicando GROUP BY.A new ObjectQuery<T> instance of type DbDataRecord that is equivalent to the original instance with GROUP BY applied.

Excepciones

El parámetro query es null o una cadena vacía.The query parameter is null or an empty string.

O bien-or- El parámetro projection es null o una cadena vacía.The projection parameter is null or an empty string.

Ejemplos

En este ejemplo se basa en el modelo AdventureWorks Sales.This example is based on the AdventureWorks Sales Model.

En este ejemplo, se crea un nuevo objeto ObjectQuery<T> que contiene los resultados de la consulta existente agrupados por nombre de producto.This example creates a new ObjectQuery<T> object that contains the results of the existing query grouped by product name.

    using (AdventureWorksEntities context =
        new AdventureWorksEntities())
    {
        string queryString = @"SELECT VALUE product 
            FROM AdventureWorksEntities.Products AS product";

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

        ObjectQuery<DbDataRecord> productQuery2 =
            productQuery.GroupBy("it.name AS pn",
            "Sqlserver.COUNT(it.Name) as count, pn");

        // Iterate through the collection of Products
        // after the GroupBy method was called.
        foreach (DbDataRecord result in productQuery2)
        {
            Console.WriteLine("Name: {0}; Count: {1}",
                result["pn"], result["count"]);
        }
    }
}
    Using context As New AdventureWorksEntities()
        Dim queryString As String = "SELECT VALUE product " & vbCr & vbLf & " FROM AdventureWorksEntities.Products AS product"

        Dim productQuery As New ObjectQuery(Of Product)(queryString, context, MergeOption.NoTracking)

        Dim productQuery2 As ObjectQuery(Of DbDataRecord) = _
            productQuery.GroupBy("it.name AS pn", "Sqlserver.COUNT(it.Name) as count, pn")

        ' Iterate through the collection of Products 
        ' after the GroupBy method was called. 
        For Each result As DbDataRecord In productQuery2
            Console.WriteLine("Name: {0}; Count: {1}", result("pn"), result("count"))
        Next
    End Using
End Sub

En este ejemplo se devuelve un conjunto de registros de datos anidados que contienen el Contact.LastName columna, agrupados y ordenados alfabéticamente por la primera letra de Contact.LastName.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.

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    // Define the query with a GROUP BY clause that returns
    // a set of nested LastName records grouped by first letter.
    ObjectQuery<DbDataRecord> query =
        context.Contacts
        .GroupBy("SUBSTRING(it.LastName, 1, 1) AS ln", "ln")
        .Select("it.ln AS ln, (SELECT c1.LastName " +
        "FROM AdventureWorksEntities.Contacts AS c1 " +
        "WHERE SubString(c1.LastName, 1, 1) = it.ln) AS CONTACT")
        .OrderBy("it.ln");

    // Execute the query and walk through the nested records.
    foreach (DbDataRecord rec in
        query.Execute(MergeOption.AppendOnly))
    {
        Console.WriteLine("Last names that start with the letter '{0}':",
                    rec[0]);
        List<DbDataRecord> list = rec[1] as List<DbDataRecord>;
        foreach (DbDataRecord r in list)
        {
            for (int i = 0; i < r.FieldCount; i++)
            {
                Console.WriteLine("   {0} ", r[i]);
            }
        }
    }
}
Using context As New AdventureWorksEntities()
    ' Define the query with a GROUP BY clause that returns 
    ' a set of nested LastName records grouped by first letter. 
    Dim query As ObjectQuery(Of DbDataRecord) = _
        context.Contacts.GroupBy("SUBSTRING(it.LastName, 1, 1) AS ln", "ln") _
        .Select("it.ln AS ln, (SELECT c1.LastName FROM AdventureWorksEntities.Contacts AS c1 " & _
                "WHERE SubString(c1.LastName, 1, 1) = it.ln) AS CONTACT").OrderBy("it.ln")

    ' Execute the query and walk through the nested records. 
    For Each rec As DbDataRecord In query.Execute(MergeOption.AppendOnly)
        Console.WriteLine("Last names that start with the letter '{0}':", rec(0))
        Dim list As List(Of DbDataRecord) = TryCast(rec(1), List(Of DbDataRecord))
        For Each r As DbDataRecord In list
            For i As Integer = 0 To r.FieldCount - 1
                Console.WriteLine(" {0} ", r(i))
            Next
        Next
    Next
End Using

Comentarios

GroupBy se aplica la proyección especificada por el projection parámetro.GroupBy applies the projection specified by the projection parameter. Esto significa que la ObjectQuery<T> devuelta por el método GroupBy siempre es de tipo DbDataRecord.This means that the ObjectQuery<T> returned by the GroupBy method is always of type DbDataRecord. Para obtener más información, consulte las consultas de objeto.For more information, see Object Queries.

Se aplica a

Consulte también: