protected void init()    {        String userid="";        String submithomework_marks = "";        String answer = "";        String attachment = "";        String sql = "select * from submithomework where homeworkid='42' and userid='450222199410300311'";        //存入数据库 1.获取路径或者答案，填入        SqlConnection conn = dc.SQL_con();        SqlCommand command = new SqlCommand(sql, conn);        //3.执行数据库查询获取返回值        conn.Open();        SqlDataReader reader = command.ExecuteReader();        if (reader.Read())        {            userid = reader["userid"].ToString();            submithomework_marks = reader["submithomework_marks"].ToString();            answer = reader["answer"].ToString();            attachment = reader["attachment"].ToString();        }        if (userid != null || userid.Equals(""))        {            TextBox1.Text = answer;        }        Response.Write("userid:" + userid);    }

某一列，某一字段