Ejemplos de sintaxis de expresiones de consulta: ordenación (LINQ to DataSet)
Los ejemplos de este tema muestran cómo se utilizan los métodos OrderBy, OrderByDescending, Reverse y ThenByDescending para consultar DataSet y ordenar los resultados utilizando la sintaxis de expresiones de consultas.
El método FillDataSet usado en estos ejemplos se especifica en Cargar datos en un conjunto de datos.
Los ejemplos de este tema utilizan las tablas Contact, Address, Product, SalesOrderHeader y SalesOrderDetail en la base de datos de ejemplo de AdventureWorks.
Los ejemplos de este tema utilizan las siguientes instrucciones using/Imports:
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Globalization;
using System.Linq;
using System.Windows.Forms;
Option Explicit On
Imports System.Linq
Imports System.Linq.Expressions
Imports System.Collections.Generic
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.Common
Imports System.Globalization
Para obtener más información, consulte Cómo: Crear un proyecto de LINQ to DataSet en Visual Studio.
OrderBy
Ejemplo
En este ejemplo se utiliza OrderBy para devolver una lista de contactos organizados por apellido.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contacts = ds.Tables["Contact"];
IEnumerable<DataRow> query =
from contact in contacts.AsEnumerable()
orderby contact.Field<string>("LastName")
select contact;
Console.WriteLine("The sorted list of last names:");
foreach (DataRow contact in query)
{
Console.WriteLine(contact.Field<string>("LastName"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim contacts As DataTable = ds.Tables("Contact")
Dim query = _
From contact In contacts.AsEnumerable() _
Select contact _
Order By contact.Field(Of String)("LastName")
Console.WriteLine("The sorted list of last names:")
For Each contact In query
Console.WriteLine(contact.Field(Of String)("LastName"))
Next
Ejemplo
En este ejemplo se utiliza OrderBy para ordenar una lista de contactos por longitud del apellido.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contacts = ds.Tables["Contact"];
IEnumerable<DataRow> query =
from contact in contacts.AsEnumerable()
orderby contact.Field<string>("LastName").Length
select contact;
Console.WriteLine("The sorted list of last names (by length):");
foreach (DataRow contact in query)
{
Console.WriteLine(contact.Field<string>("LastName"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim contacts As DataTable = ds.Tables("Contact")
Dim query = _
From contact In contacts.AsEnumerable() _
Select contact _
Order By contact.Field(Of String)("LastName").Length
Console.WriteLine("The sorted list of last names (by length):")
For Each contact In query
Console.WriteLine(contact.Field(Of String)("LastName"))
Next
OrderByDescending
Ejemplo
En este ejemplo se utiliza orderby… descending (Order By … Descending), equivalente al método OrderByDescending, para ordenar el precio de venta de mayor a menor.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable products = ds.Tables["Product"];
IEnumerable<Decimal> query =
from product in products.AsEnumerable()
orderby product.Field<Decimal>("ListPrice") descending
select product.Field<Decimal>("ListPrice");
Console.WriteLine("The list price from highest to lowest:");
foreach (Decimal product in query)
{
Console.WriteLine(product);
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim products As DataTable = ds.Tables("Product")
Dim query = _
From product In products.AsEnumerable() _
Select product _
Order By product.Field(Of Decimal)("ListPrice") Descending
Console.WriteLine("The list price From highest to lowest:")
For Each product In query
Console.WriteLine(product.Field(Of Decimal)("ListPrice"))
Next
Reverse
Ejemplo
En este ejemplo se utiliza Reverse para crear una lista de pedidos en los que OrderDate es anterior al 20 de febrero de 2002.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable orders = ds.Tables["SalesOrderHeader"];
IEnumerable<DataRow> query = (
from order in orders.AsEnumerable()
where order.Field<DateTime>("OrderDate") < new DateTime(2002, 02, 20)
select order).Reverse();
Console.WriteLine("A backwards list of orders where OrderDate < Feb 20, 2002");
foreach (DataRow order in query)
{
Console.WriteLine(order.Field<DateTime>("OrderDate"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim orders As DataTable = ds.Tables("SalesOrderHeader")
Dim query = ( _
From order In orders.AsEnumerable() _
Where order.Field(Of DateTime)("OrderDate") < New DateTime(2002, 2, 20) _
Select order).Reverse()
Console.WriteLine("A backwards list of orders where OrderDate < Feb 20, 2002")
For Each order In query
Console.WriteLine(order.Field(Of DateTime)("OrderDate"))
Next
ThenByDescending
Ejemplo
En este ejemplo se utiliza OrderBy… Descending, que es equivalente al método ThenByDescending, para ordenar una lista de productos, primero por nombre y después por precio de venta, de mayor a menor.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable products = ds.Tables["Product"];
IEnumerable<DataRow> query =
from product in products.AsEnumerable()
orderby product.Field<string>("Name"),
product.Field<Decimal>("ListPrice") descending
select product;
foreach (DataRow product in query)
{
Console.WriteLine("Product ID: {0} Product Name: {1} List Price {2}",
product.Field<int>("ProductID"),
product.Field<string>("Name"),
product.Field<Decimal>("ListPrice"));
}
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim products As DataTable = ds.Tables("Product")
Dim query = _
From product In products.AsEnumerable() _
Order By product.Field(Of String)("Name"), _
product.Field(Of Decimal)("ListPrice") Descending _
Select product
For Each product In query
Console.Write("Product ID: " & product.Field(Of Integer)("ProductID"))
Console.Write(" Product Name: " & product.Field(Of String)("Name"))
Console.WriteLine(" List Price: " & product.Field(Of Decimal)("ListPrice"))
Next