using System;
using System.Data;
using System.Configuration;
using System.Collections;
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 adminmofiy : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
      
            string str = ConfigurationSettings.AppSettings["dsn"];
            SqlConnection cn = new SqlConnection(str);
            cn.Open();
          int straid = Convert.ToInt32(Request.QueryString["aid"].ToString());
            string mysql = "SELECT * FROM admin WHERE (aid =" + straid + ")";
            // SELECT * FROM Goods WHERE (GID = '10001')
            SqlCommand cm = new SqlCommand(mysql, cn);
            // = CommandType.StoredProcedure;
            //cm.Parameters.Add("@GID", SqlDbType.Int);
            //cm.Parameters["@GID"].Value = Convert.ToInt32(Request.QueryString["gid"].ToString());
            SqlDataReader dr = cm.ExecuteReader();
            if (dr.Read())
            {
               lbl_aid.Text = dr["aid"].ToString();
                T_aname.Text = dr["aname"].ToString();
                T_apassword.Text = dr["apassword"].ToString();
                T_apower.Text = dr["apower"].ToString();
                T_adep.Text = dr["adep"].ToString();
               
            }
            else
            {
                Response.Write("对不起，没有该人员信息");
                Response.End();
            }

        }
int straid = Convert.ToInt32(Request.QueryString["aid"].ToString());这一行报错

查看网页的地址栏，看看地址里有没有   ?aid=5 之类的

Request.QueryString["aid"] 确定这个不是空的吗？

我试试

if (Request.QueryString["aid"] != null)
{
    int straid = Convert.ToInt32(Request.QueryString["aid"].ToString());
}
首先做一下是否为null的判断，记得再判断下值是否是数字，这些判断很重要，如果不符合要求，就不要执行代码

aid 好像是空的，怎么办啊，是不是数据库连接有问题

数据库连接没有问题我试过了。
当前上下文中不存在名称“straid”
 int straid = Convert.ToInt32(Request.QueryString["aid"].ToString());
行 24:             }
行 25:             string mysql = "SELECT * FROM admin WHERE (aid =" + straid + ")";
行 26:             // SELECT * FROM Goods WHERE (GID = '10001')
行 27:             SqlCommand cm = new SqlCommand(mysql, cn);
怎么回事啊，不太明白，高手帮帮吧

3楼和5楼不是说了吗？在前面加个判断就得了。
如果传过来的aid是空，就不做下面的处理，显示个错误啥的不就行了？？

int straid = Convert.ToInt32(Request.QueryString["aid"].ToString());
行 24:             }
从24行的 } 来看，估计straid是个局部变量,它的作用范围太小，不能被 string mysql = "SELECT * FROM admin WHERE (aid =" + straid + ")";引用

LS明显在乱说。