本主题中的示例演示如何使用 First 方法通过使用查询表达式语法以查询 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。
First
示例
以下示例使用 First 方法以返回其名字为“Brooke”的第一个联系人。
Using AWEntities As New AdventureWorksEntities
Dim contacts As ObjectQuery(Of Contact) = AWEntities.Contact
Dim query As Contact = ( _
From cont In contacts _
Where cont.FirstName = "Brooke" _
Select cont).First()
Console.WriteLine("ContactID: " & query.ContactID)
Console.WriteLine("FirstName: " & query.FirstName)
Console.WriteLine("LastName: " & query.LastName)
End Using
using (AdventureWorksEntities AWEntities = new AdventureWorksEntities())
{
ObjectQuery<Contact> contacts = AWEntities.Contact;
Contact query = (
from contact in contacts
where contact.FirstName == "Brooke"
select contact)
.First();
Console.WriteLine("ContactID: " + query.ContactID);
Console.WriteLine("FirstName: " + query.FirstName);
Console.WriteLine("LastName: " + query.LastName);
}