初识Linq

Hello Linq：

using System;using System.Linq;namespace HelloLinq{ class Program { static void Main(string[] args) { string[] greetings = { "Hello world", "Hello LINQ", "Hello Apress" }; var items = from s in greetings where s.EndsWith("LINQ") select s; foreach (var item in items) Console.WriteLine(item); } }}

 Linq in XML:

using System;using System.Linq;using System.Xml.Linq;namespace XMLLinq{ class Program { static void Main(string[] args) { XElement books = XElement.Parse( @"<books> <book> <title>Pro LINQ: Language Integrated Query in C# 2008</title> <author>Joe Rattz</author> </book> <book> <title>Pro WF: Windows Workflow in .NET 3.0</title> <author>Bruce Bukovics</author> </book> <book> <title>Pro C# 2005 and the .NET 2.0 Platform, Third Edition</title> <author>Andrew Troelsen</author> </book> </books>"); var titles = from book in books.Elements("book") where (string)book.Element("author") == "Joe Rattz" select book.Element("title"); foreach (var title in titles) Console.WriteLine(title.Value); } }}

 Linq in SQLServer:

看实例之前先来了解下如何生成数据库实例类

sqlmetal /server:. /database:Northwind /namespace:nwind /code:Northwind.cs /pluralize /functions /sprocs /views /user:sa /password:123456将会在VS目录下生成一个Northwind.cs文件，此命令需在 Visual Studio 2008 命令提示 下输入

生成了类文件，我们来看Linq查询Sql Server的代码

using System;using System.Linq;using System.Data.Linq;using nwind;namespace SqlLinq{ class Program { static void Main(string[] args) { Northwind db = new Northwind(@"Data Source=.;DataBase=Northwind;Uid=sa;Pwd=sa2008"); var custs = from c in db.Customers where c.City == "Rio de Janeiro" select c; foreach (var cust in custs) Console.WriteLine("{0}", cust.CompanyName); } }}

using System.Data.Linq;需要添加引用System.Data.Linq

 

Linq的三大查询介绍完了，接下去要具体学习各个查询了