以方法為基礎的查詢語法範例：轉換
本主題中的範例示範如何使用 ToArray、ToDictionary 和 ToList 方法，透過以方法為基礎的查詢語法來查詢 AdventureWorks Sales 模型。 這些範例中使用的 AdventureWorks Sales Model 是從 AdventureWorks 範例資料庫中的 Contact、Address、Product、SalesOrderHeader 和 SalesOrderDetail 資料表所建立。
此主題中的範例使用下列 using/Imports 陳述式：
using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using System.Globalization;
using System.Data.EntityClient;
using System.Data.SqlClient;
using System.Data.Common;
Option Explicit On
Option Strict On
Imports System.Data.Objects
Imports System.Globalization
ToArray
範例
以下範例使用 ToArray 方法將序列立即評估為陣列。
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
ObjectSet<Product> products = context.Products;
Product[] prodArray = (
from product in products
orderby product.ListPrice descending
select product).ToArray();
Console.WriteLine("Every price from highest to lowest:");
foreach (Product product in prodArray)
{
Console.WriteLine(product.ListPrice);
}
}
Using context As New AdventureWorksEntities
Dim products As ObjectSet(Of Product) = context.Products
Dim prodArray As Product() = ( _
From product In products _
Order By product.ListPrice Descending _
Select product).ToArray()
Console.WriteLine("The list price from highest to lowest:")
For Each prod As Product In prodArray
Console.WriteLine(prod.ListPrice)
Next
End Using
ToDictionary
範例
下列範例會使用 ToDictionary 方法，立即將序列和相關的索引鍵運算式評估為字典。
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
ObjectSet<Product> products = context.Products;
Dictionary<String, Product> scoreRecordsDict = products.
ToDictionary(record => record.Name);
Console.WriteLine("Top Tube's ProductID: {0}",
scoreRecordsDict["Top Tube"].ProductID);
}
Using context As New AdventureWorksEntities
Dim products As ObjectSet(Of Product) = context.Products
Dim scoreRecordsDict As Dictionary(Of String, Product) = _
products.ToDictionary(Function(record) record.Name)
Console.WriteLine("Top Tube's ProductID: {0}", _
scoreRecordsDict("Top Tube").ProductID)
End Using
ToList
範例
下列範例會使用 ToList 方法，立即將序列評估為 List<T>，其中 T 的型別為 DataRow。
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
ObjectSet<Product> products = context.Products;
List<Product> query =
(from product in products
orderby product.Name
select product).ToList();
Console.WriteLine("The product list, ordered by product name:");
foreach (Product product in query)
{
Console.WriteLine(product.Name.ToLower(CultureInfo.InvariantCulture));
}
}
Using context As New AdventureWorksEntities
Dim products As ObjectSet(Of Product) = context.Products
Dim prodList As List(Of Product) = ( _
From product In products _
Order By product.Name _
Select product).ToList()
Console.WriteLine("The product list, ordered by product name:")
For Each prod As Product In prodList
Console.WriteLine(prod.Name.ToLower(CultureInfo.InvariantCulture))
Next
End Using