查询表达式语法示例：排序 (LINQ to Entities)

2008-08-22

本主题中的示例演示如何使用 OrderBy 和 OrderByDescending 方法以通过查询表达式语法来查询 AdventureWorks 销售模型。这些示例中使用的 AdventureWorks 销售模型从 AdventureWorks 示例数据库中的 Contact、Address、Product、SalesOrderHeader 和 SalesOrderDetail 等表生成。

本主题中的示例使用下面的 using/Imports 语句：

Option Explicit On
Option Strict On
Imports L2EExamplesVB.AdventureWorksModel
Imports System.Data.Objects
Imports System.Globalization

using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using AdventureWorksModel;
using System.Globalization;

有关更多信息，请参见如何：在 Visual Studio 中创建 LINQ to Entities 项目。

OrderBy

示例

以下示例使用 OrderBy 以返回按姓氏排序的联系人列表。

Using AWEntities As New AdventureWorksEntities
    Dim contacts As ObjectQuery(Of Contact) = AWEntities.Contact

    Dim sortedContacts = _
        From contact In contacts _
        Order By contact.LastName _
        Select contact

    Console.WriteLine("The sorted list of last names:")
    For Each n As Contact In sortedContacts
        Console.WriteLine(n.LastName)
    Next
End Using

using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
    ObjectQuery<Contact> contacts = AWEntities.Contact;

    IQueryable<Contact> sortedNames =
        from n in contacts
        orderby n.LastName
        select n;

    Console.WriteLine("The sorted list of last names:");
    foreach (Contact n in sortedNames)
    {
        Console.WriteLine(n.LastName);
    }
}

示例

以下示例使用 OrderBy 以按姓氏的长度对联系人列表排序。

Using AWEntities As New AdventureWorksEntities
    Dim contacts As ObjectQuery(Of Contact) = AWEntities.Contact

    Dim sortedNames = _
        From n In contacts _
        Order By n.LastName.Length _
        Select n

    Console.WriteLine("The sorted list of last names (by length):")
    For Each n As Contact In sortedNames
        Console.WriteLine(n.LastName)
    Next
End Using

using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
    ObjectQuery<Contact> contacts = AWEntities.Contact;

    IQueryable<Contact> sortedNames =
        from n in contacts
        orderby n.LastName.Length
        select n;

    Console.WriteLine("The sorted list of last names (by length):");
    foreach (Contact n in sortedNames)
    {
        Console.WriteLine(n.LastName);
    }
}

OrderByDescending

示例

以下示例使用 orderby… descending（等效于 OrderByDescending 方法，但在 Visual Basic 中为 Order By … Descending），以按照从高到低的顺序对价目表排序。

Using AWEntities As New AdventureWorksEntities
    Dim products As ObjectQuery(Of Product) = AWEntities.Product

    Dim sortedPrices = _
        From product In products _
        Order By product.ListPrice Descending _
        Select product.ListPrice

    Console.WriteLine("The list price from highest to lowest:")
    For Each price As Decimal In sortedPrices
        Console.WriteLine(price)
    Next
End Using

using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
    ObjectQuery<Product> products = AWEntities.Product;

    IQueryable<Decimal> sortedPrices =
        from p in products
        orderby p.ListPrice descending
        select p.ListPrice;

    Console.WriteLine("The list price from highest to lowest:");
    foreach (Decimal price in sortedPrices)
    {
        Console.WriteLine(price);
    }
}

ThenBy

示例

以下示例使用 OrderBy 和 ThenBy 以返回先按姓氏后按名字排序的联系人列表。

Using AWEntities As New AdventureWorksEntities
    Dim contacts As ObjectQuery(Of Contact) = AWEntities.Contact

    Dim sortedContacts = _
        From contact In contacts _
        Order By contact.LastName, contact.FirstName _
        Select contact

    Console.WriteLine("The list of contacts sorted by last name then by first name:")
    For Each sortedContact As Contact In sortedContacts
        Console.WriteLine(sortedContact.LastName + ", " + sortedContact.FirstName)
    Next
End Using

using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
    ObjectQuery<Contact> contacts = AWEntities.Contact;

    IQueryable<Contact> sortedContacts =
        from contact in contacts
        orderby contact.LastName, contact.FirstName
        select contact;

    Console.WriteLine("The list of contacts sorted by last name then by first name:");
    foreach (Contact sortedContact in sortedContacts)
    {
        Console.WriteLine(sortedContact.LastName + ", " + sortedContact.FirstName);
    }
}

ThenByDescending

示例

以下示例使用 OrderBy… Descending（等效于 ThenByDescending 方法），以先按名称后按标价（从高到低）对产品列表排序。

Using AWEntities As New AdventureWorksEntities
    Dim products As ObjectQuery(Of Product) = AWEntities.Product

    Dim query As IQueryable(Of Product) = _
        From product In products _
        Order By product.Name, product.ListPrice Descending _
        Select product

    For Each prod As Product In query
        Console.WriteLine("Product ID: {0} Product Name: {1} List Price {2}", _
            prod.ProductID, _
            prod.Name, _
            prod.ListPrice)
    Next
End Using

using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
    ObjectQuery<Product> products = AWEntities.Product;

    IQueryable<Product> query =
        from product in products
        orderby product.Name, product.ListPrice descending
        select product;

    foreach (Product product in query)
    {
        Console.WriteLine("Product ID: {0} Product Name: {1} List Price {2}",
            product.ProductID,
            product.Name,
            product.ListPrice);
    }
}

另请参见

概念

查询表达式语法示例 (LINQ to Entities)

通过