dr.Close();
            
myConnection.Close();
两句放在if内

改了以后还是分析器错误
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

namespace cha1
{
    /// <summary>
    /// WebForm1 的摘要说明。
    /// </summary>
    public class WebForm1 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.DropDownList uidlist;
        protected System.Web.UI.WebControls.TextBox txtname;
        protected System.Web.UI.WebControls.TextBox txtadress;
        protected System.Web.UI.WebControls.TextBox txtcontent;

        private void Page_Load(object sender, System.EventArgs e)
        {
            if(!IsPostBack)
            {
                SqlConnection myConnection=new SqlConnection("server=TY;uid=sa;pwd=sa;database=北风贸易;");
                SqlCommand myCommand = new SqlCommand("SELECT 身份证号码,姓名,家庭住址,自传 FROM 飞狐工作室", MyConnection);
                myConnection.Open();
                SqlDataReader dr=myCommand.ExecuteReader();
                bool firstrow=true;
                while(firstrow)
                {
                    txtname.Text=dr[1].ToString();
                    txtadress.Text=dr[2].ToString();
                    txtcontent.Text=dr[3].ToString();
                    firstrow=false;
                }
            
                dr.Close();
            
                myConnection.Close();
            }
        }

你的代码没贴全？这样也能编译通过吗？

   
        private void UidList_SelectedIndexChanged(object sender, System.EventArgs e)
        {
            SqlConnection myConnection = new SqlConnection("workstation id=TY;packet size=4096;integrated security=SSPI;data source=TY;persist security info=True;initial catalog=北风贸易;Trusted_Connection=yes");
            SqlCommandmyCommand = new SqlCommand("SELECT 身份证号码,姓名,家庭住址,自传 FROM 飞狐工作室 WHERE 身份证号码 = @uid", MyConnection);
            
            string uid;
            uid = UidList.SelectedItem.Text;
            myCommand.Parameters.Add("@uid", SqlDbType.NVarChar, 18).Value = uid;
            myConnection.Open();
            SqlDataReader dr = myCommand.ExecuteReader(CommandBehavior.SingleRow);
            if (dr.Read())
            {
                txtname.Text = (string)dr[1];
                txtaddress.Text = (string)dr[2];
                if (Convert.IsDBNull(dr[3]))
                    txtcontent.Text = "";
                else
                  txtcontent.Text = (string)dr[3];
            
                dr.Close();
                myConnection.Close();
            }
        }
    }
}

这是后面的代码

请指教，谢谢！！