SqlConnection,SqlCommand,SqldataReader的用法总结: 
希望对新手有所帮助!!!

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {

        //--------------------------------SqlConnection,SqlCommand,SqlDataAdaper的用法------------//

        //下面的3种形式等价,如果你的数据库是Windows连接方法,直接把连接字符串改成"server=.;database=northwind;integrated security=true;"
        //如果你的数据库是某个实例名,直接把"server=."改成"server=你的计算机名实例名"就可以了

        //SqlConnection con = new SqlConnection("server=.;database=northwind;uid=sa;pwd=;");
        //con.Open();
        //SqlDataAdapter sda = new SqlDataAdapter("select * from customers", con);
        //DataSet ds = new DataSet();
        //sda.Fill(ds, "customers");
        ////下面这5个语句等价
        ////this.GridView1.DataSource = ds;
        ////this.GridView1.DataSource = ds.Tables[0];
        ////this.GridView1.DataSource = ds.Tables["customers"];
        ////this.GridView1.DataSource = ds.Tables[0].DefaultView;
        //this.GridView1.DataSource = ds.Tables["customers"].DefaultView;
        //this.GridView1.DataBind();
        //con.Close();

        //SqlConnection con = new SqlConnection("server=.;database=northwind;uid=sa;pwd=;");
        //con.Open();
        //SqlCommand cmd = new SqlCommand("select * from customers", con);
        //SqlDataAdapter sda = new SqlDataAdapter();
        //sda.SelectCommand = cmd;
        //DataSet ds = new DataSet();
        //sda.Fill(ds, "customers");
        //this.GridView1.DataSource = ds.Tables["customers"].DefaultView;
        //this.GridView1.DataBind();
        //con.Close();

        //SqlConnection con = new SqlConnection("server=.;database=northwind;uid=sa;pwd=;");
        //con.Open();
        //SqlDataAdapter sda = new SqlDataAdapter();
        //sda.SelectCommand = new SqlCommand("select * from customers", con);
        //DataSet ds = new DataSet();
        //sda.Fill(ds, "customers");
        //this.GridView1.DataSource = ds.Tables["customers"].DefaultView;
        //this.GridView1.DataBind();
        //con.Close();
}以上四种方法都可以把数据库中的数据读出来,绑定到GridView控件!!!