C#如何访问access中的货币字段 - .NET技术 / C#

下面这段代码是想实现读取数据库表中的货币字段money， 并进行更新，但是调试时总在读取money时出错（黄色处），大家帮忙看看，谢谢了~~
db1.oleDbConnection1.Open();
  OleDbCommand cmd = new OleDbCommand("select lb.Account,money,LendDate from lb,reader where lb.Account=reader.[account]",db1.oleDbConnection1 );
  OleDbDataReader dr = cmd.ExecuteReader();
  while (dr.Read())
  {
  DateTime t_m = dr.GetDateTime(2);
  string money_m =dr.GetString (1); string account_m=dr.GetString (0);
  DateTime t_now = DateTime.Now;
  int days = DateDiff(t_m ,t_now );
  if (days > 30)
  {

  string fee = Convert.ToString((days - 30) * 0.1 + money_m);
  OleDbCommand cmd1= new OleDbCommand(string .Format ("update reader set money ='{0}' where [account]='{1}' ",fee,account_m ), db1.oleDbConnection1);
  cmd1.ExecuteNonQuery();

  }
  }
  dr.Close();
  db1.oleDbConnection1.Close();

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黄色处本是 double money_m =dr.Getdouble (1);粘错了……

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什么错误提示？

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引用

什么错误提示？