使用sqlCommand对象查询数据示例

```asp.net
using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.Sql;
using System.Data.SqlClient;

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

protected void Button1_Click(object sender, EventArgs e)
{
    //1.连接数据库
    SqlConnection myCon = new SqlConnection();
    myCon.ConnectionString=ConfigurationManager.ConnectionStrings["ConnectionString"].ToString();
    myCon.Open();
    //2.实例化一个sqlcommand对象
    SqlCommand myCom = new SqlCommand();
    //3.利用查询命令赋值sqlCommand的commandText
    myCom.Connection = myCon;
    myCom.CommandText = "select * from students";
    //4.查询，并查看是否成功
    SqlDataReader sdr = myCom.ExecuteReader();
    if (sdr.Read())
        Response.Write("查询成功！");
    else
        Response.Write("查询失败！");
  /*
    //4.查询，并查看是否成功
    SqlDataReader sdr = myCom.ExecuteReader();
    if (sdr.Read())
        Response.Write("查询成功！");
    else
        Response.Write("失败！");
   */
    //4.查询，并输出结果
    SqlDataReader sdr = myCom.ExecuteReader();
    Response.Write("<table border=1px>");
    Response.Write("<tr>");
    Response.Write("<td>" + "Sno" + "</td>");
    Response.Write("<td>" + "Sname" + "</td>");
    Response.Write("</tr>");
    while (sdr.Read())
    {
        Response.Write("<tr>");
        Response.Write("<td>" + sdr.GetString(sdr.GetOrdinal("Sno")) + "</td>");
        Response.Write("<td>" + sdr.GetString(sdr.GetOrdinal("Sname")) + "</td>");
        Response.Write("</tr>");

    }
    //5.断开连接
    myCon.Close();
}

}
```