Question

即使我的DataReader似乎正确地解释了这些值（差不多），但是它缺少一个列，没有写入文件，而在最后一行它正在抛出一个

+ base {"Invalid attempt to read when no data is present."} System.SystemException {System.InvalidOperationException}

因为它退出while sqlReader.Read()循环。

myCommand.CommandText = "use sis_comparison_data select reg_batch_uid, user_id_reg, reg_first, reg_mid, reg_last, reg_email, reg_stu_id, registrar_row_status from sis_temp where bb_row_status is null";

string bb_users = @"C:\BB_USERS.bbd";


  using (StreamWriter file = new StreamWriter(bb_users, false))
  {
    file.WriteLine("SYSTEM_ROLE|INSTITUTION_ROLE|EXTERNAL_PERSON_KEY|USER_ID|PASSWD|FIRSTNAME|MIDDLENAME|LASTNAME|EMAIL|STUDENT_ID|ROW_STATUS");
    using (SqlDataReader sqlReader = myCommand.ExecuteReader())
            {
            while (sqlReader.Read())
                {
                    file.WriteLine("none|student|", sqlReader["reg_batch_uid"].ToString() + "|" + sqlReader["user_id_reg"].ToString() + "|" + sqlReader["reg_stu_id"].ToString() + "|" + sqlReader["reg_first"].ToString() + "|" + sqlReader["reg_mid"].ToString() + "|" + sqlReader["reg_last"].ToString() + "|" + sqlReader["reg_email"].ToString() + "|" + sqlReader["reg_stu_id"].ToString() + "|" + sqlReader["registrar_row_status"].ToString());
                }
                sqlReader.Close();
            }             
   }

我的代码是创建文件并编写第一行，并且在它之后只写了"none|student|"。无论出于何种原因，它都不会拿起registrar_row_status列。

SQL查询的工作原理是我在将所有SQL脚本编写到代码之前就已经完成了所有SQL脚本。

这是调试输出在单步执行代码时显示的内容。

+       sqlReader   {System.Data.SqlClient.SqlDataReader}   System.Data.SqlClient.SqlDataReader
        sqlReader["reg_batch_uid"]  "johndoe"   object {string}
        sqlReader["reg_email"]  "jdoe@com.edu"  object {string}
        sqlReader["reg_first"]  "john"  object {string}
        sqlReader["reg_last"]   "doe"   object {string}
        sqlReader["reg_mid"]    ""  object {string}
        sqlReader["reg_stu_id"] "1234567"   object {string}
        sqlReader["user_id_reg"]    "johndoe"   object {string}

如您所见，它缺少registrar_row_status

Answer 1

我相信你StreamWriter.WriteLine重载的第一个参数需要是一个格式字符串。请参阅the documentation。

Answer 2

试试这个：

 file.WriteLine("none|student|" + sqlReader["reg_batch_uid"].ToString() + "|" + sqlReader["user_id_reg"].ToString() + "|" + sqlReader["reg_stu_id"].ToString() + "|" + sqlReader["reg_first"].ToString() + "|" + sqlReader["reg_mid"].ToString() + "|" + sqlReader["reg_last"].ToString() + "|" + sqlReader["reg_email"].ToString() + "|" + sqlReader["reg_stu_id"].ToString() + "|" + sqlReader["registrar_row_status"].ToString());

SQL DataReader不读取所有列，也不会写入文件

2 个答案: