译:在C#中使用LINQ To SQL

译文出处:http://www.codeproject.com/Tips/871938/LINQ-To-SQL-Using-Csharp

 今天在这个话题中,我给大家分享一个在c#编程中非常有趣和十分有用的特性。

开始之前,我想告诉大家关于Linq的基本信息。比如:什么是linq?然后再来分享实际应用。

说明:

LINQ = Language Integrated Query集成查询语言

Linq是微软在.NET Framework 3.5中信增加的一个特性。它是用来查询数据库和对数据库查询的本地集合带来安全性。它非常简单但是很有组织性。一个普通的查询语言,适用于SQL, XML, 本地collections 和 第三方APIs 比如SharePoint.

本质上,Linq提供的就是一个轻量级的编程数据集成。这是非常有价值的,尤其是当今每天面对的数据和未来的大数据。

接下来我们就看看这个神秘的东东。

第一步:

 

  • 打开你的Visual Studio 并且创建一个新的控制台项目.
  • 然后打开服务器资源管理,创建一个新的数据库,新增一张表增加几个字段。
  • 打开你的项目的解决方案目录,右击工程点击添加新增项。
  • 查找LINQ-To-SQL 并添加。
  • 你会看到一个空白的文件,在这个文件中你可以拖动你的表放在 LINQ-To-SQL .dbml 文件扩展上.

第二步:

我将声明一些类,添加一些类成员。

1 class Program
2     {                            // this is  program class
3         private int id;
4         private string name;
5         private string fname;
6         private int age;
7         private string sem;
8 }

第三步:

这里我将告诉大家如何通过 LINQ-To-SQL 向数据库中插入数据。

 1 public void insert()
 2         {
 3 // these are the class data members through we will send our objects data in the database
 4             Console.WriteLine("Enter id");
 5             id = Convert.ToInt32(Console.ReadLine());
 6             Console.WriteLine("Enter name");
 7             name = Console.ReadLine();
 8             Console.WriteLine("Enter father name");
 9             fname = Console.ReadLine();
10             Console.WriteLine("Enter age");
11             age = Convert.ToInt32(Console.ReadLine());
12             Console.WriteLine("Enter semester");
13             sem = Console.ReadLine();
14 // this is the data context class the main class which handles 
15 // all the functionality in this will pass the connection string of our database file.
16             LTSDataContext LTS = new LTSDataContext
17             (@"Data Source=(LocalDB)\v11.0;
18             AttachDbFilename=C:\Users\Ehtesham Mehmood\Documents\Visual Studio 2012\Projects\
19             ConsoleApplication5\ConsoleApplication5\SDatabase.mdf;
20         Integrated Security=True;Connect Timeout=30");
21         // this is the table class which we drag on our linq to sql file
22             Student objStudentTable = new Student();
23             objStudentTable.Id = id;
24             objStudentTable.Name = name;
25             objStudentTable.Father_Name = fname;
26             objStudentTable.Age = age;
27             objStudentTable.Semester = sem;
28             LTS.Students.InsertOnSubmit(objStudentTable); // this is built in function.
29             LTS.SubmitChanges();// here is the final query will run in the data context class.
30         }

第四步:展示数据

 

 1 void Display()
 2         {
 3             LTSDataContext LTS = new LTSDataContext(@"Data Source=(LocalDB)\v11.0;
 4             AttachDbFilename=C:\Users\Ehtesham Mehmood\Documents\Visual Studio 2012\Projects\
 5             ConsoleApplication5\ConsoleApplication5\SDatabase.mdf;
 6         Integrated Security=True;Connect Timeout=30");
 7             var selectQuery = from s in LTS.Students
 8                               select s;
 9             foreach (Student s in selectQuery)
10             {
11                 Console.WriteLine(s.Id + "\t" + s.Name + "\t" + 
12         s.Father_Name + "\t" + s.Age + "\t" + s.Semester);
13             }
14         }

第五步:删除数据

 

 1 void Delete()
 2         {
 3             int iid = 0;
 4             Console.WriteLine("Enter the Id of the student u want to delete?");
 5             iid = Convert.ToInt32(Console.ReadLine());
 6 
 7             LTSDataContext LTS = new LTSDataContext(@"Data Source=(LocalDB)\v11.0;
 8             AttachDbFilename=C:\Users\Ehtesham Mehmood\Documents\Visual Studio 2012\Projects\
 9             ConsoleApplication5\ConsoleApplication5\SDatabase.mdf;
10         Integrated Security=True;Connect Timeout=30");
11             var delete = from p in LTS.Students
12                          where p.Id == iid
13                          select p;
14             LTS.Students.DeleteAllOnSubmit(delete);
15             LTS.SubmitChanges();
16             Student objStudentTable = LTS.Students.Single(c=> c.Id == iid);    
17         }

第六步:更新数据

 

 1 void update()
 2         {
 3             LTSDataContext LTS = new LTSDataContext(@"Data Source=(LocalDB)\v11.0;
 4             AttachDbFilename=C:\Users\Ehtesham Mehmood\Documents\Visual Studio 2012\Projects\
 5             ConsoleApplication5\ConsoleApplication5\SDatabase.mdf;
 6         Integrated Security=True;Connect Timeout=30");
 7             Student objStudentTable = new Student();
 8             int iid = 0;
 9             Console.WriteLine("Enter the Id of the student u want to update ?");
10             iid = Convert.ToInt32(Console.ReadLine());
11 
12             Console.WriteLine("Enter the new name of the student u want to update?");
13             string up = (Console.ReadLine());
14                 var update = from s1 in LTS.Students
15                              where s1.Id == iid
16                              select s1;
17                 foreach (var v in update)
18                     v.Name = up;
19                 LTS.SubmitChanges();
20         }

主函数:

 

1 static void Main(string[] arg){
2             
3            Program p1 = new Program();     // creates object 
4            p1.insert();
5            p1.Display();
6            p1.Delete();
7            p1.update();
8             Console.ReadKey();
9         }

感谢您的阅读,请留下您的足迹。

Cheers! Enjoy coding. Smile | :)

 

 

posted @ 2015-02-05 11:54  IT少年  阅读(3632)  评论(0编辑  收藏  举报