是数据库教程连接字符串，必要的如下：
New   SqlConnection( "Server=LocalHost;DataBase=Pubs;UID=sa;PWD=123 ")

下面先看个实例

SqlConnection conn = new SqlConnection();
        conn.ConnectionString = "Data Source=(local);Initial Catalog=news;User ID=sa;Password=123";

        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;

        for (int i=0;i<=GridView1.Rows.Count-1;i++)
        {
           CheckBox cbox=(CheckBox)GridView1.Rows [i].FindControl ("CheckBox1");
           if (cbox.Checked == true)
           {
             
               cmd.CommandText = "update 主题表 set 审核='已审核' where 主帖编号="+GridView1 .DataKeys[i].Value;
               conn.Open();
               cmd.ExecuteReader();
               conn.Close();
           }
       
        }

我们对上面实例一句句解析说明

1、建立一个数据库连接对象 conn
2、指定欲连接的数据库参数：服务器为本地服务器，数据库名'news’，用户ID为'sa'，密码为'123'
3、建立一个Command对象 cmd
4、将cmd的Connection变量赋值为第1步建立的对象conn
5、for循环遍历GridView1控件里的每一行
6、获得GridView1第i行里的‘CheckBox1’属性
7、判断CheckBox是否选中
8、为cmd指定执行内容，更新数据库‘主题表’里‘主帖编号’="+GridView1 .DataKeys[i].Value的那一行里‘审核’字段内容为‘已审核’
9、连接数据库
10、执行第8步指定的内容
11、关闭数据库连接

好了综合上述我们写个完整的实例

<%@ Page Language="C#" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SqlClient" %>
<%@ import Namespace="System.Data.OleDb" %>
<%@ import Namespace="System.Data.Odbc" %>





   

       

Properties from the MSDE Connection
       

       

---

       

       

       

From SqlConnection
       

       
           
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
           
       

ConnectionString:	<asp教程:Label id="lblSqlConnectionString" runat="server">ConnectionString
ConnectionTimeout:	ConnectionTimeout
Database:	Database
DataSource:	DataSource
PacketSize:	PacketSize
ServerVersion:	ServerVersion
State:	State
WorkstationId:	WorkstationId

       

       

       

From OleDbConnection
       

       
           
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
           
       

ConnectionString:	ConnectionString
ConnectionTimeout:	ConnectionTimeout
Database:	Database
DataSource:	DataSource
Provider:	Provider
ServerVersion:	ServerVersion
State:	State

       

       

       

From OdbcConnection
       

       
           
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
               
                   
                   
               
           
       

ConnectionString:	ConnectionString
ConnectionTimeout:	ConnectionTimeout
Database:	Database
DataSource:	DataSource
Driver:	Driver
ServerVersion:	ServerVersion
State:	State