Linq To SQL 入门(1)

1、首先创建数据库DataTest，下面为DataTest数据库中的表Admin:



在使用Linq操作数据库时，应当将映入System.Data.Linq命名空间。

2、添加和Admin对应的类Admin(当然也可以用其它类名);



3、用Linq开始对数据库进行常见操作：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.Linq.Mapping;
using System.Data.Linq;

public partial class Linq操作 : System.Web.UI.Page
{
//在创建DataContext对象是并初始化，其中参数为连接字符串
DataContext dc = new DataContext(@"Data Source=.\SQLEXPRESS;AttachDbFilename=E:\程序练习\LinqInAction\WebLinq\App_Data\DataTest.mdf;Integrated Security=True;User Instance=True");
protected void Page_Load(object sender, EventArgs e)
{
//调用方法添加数据
InsertData();
Gridview1.DataSource = SelectData();
Gridview1.DataBind();
}
//对Admin表进行查询
public IQueryable<Admin> SelectData()
{
Table<Admin> table=dc.GetTable<Admin>();
var query = from tab in table
select tab;
return query;
}

//插入数据
public void InsertData()
{
Table<Admin> table = dc.GetTable<Admin>();
Admin admin = new Admin();
admin.ID = 10;
admin.UserName = "xiaohai";
admin.PassWord="55555";

table.InsertOnSubmit(admin);
dc.SubmitChanges();

}

//删除数据
public void DeleteData()
{
Table<Admin> table = dc.GetTable<Admin>();
var text=from temp in table   //此时的text为Iqueryable<Admin>类型的集合
where temp.ID==10   //注意此处为"=="
select temp;
foreach (Admin admin in text)
{
table.DeleteOnSubmit(admin);
}
dc.SubmitChanges();
}
}