access c# update 简单错误 请教。

access数据库 c# vs2008

  protected void tongji1(object sender, EventArgs e)
  {
  string constr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=e:\\dbps.mdb";
  string str = "UPDATE table1 SET number =number + 1 where id = 1 ";
  OleDbConnection conn = new OleDbConnection(constr);

  conn.Open();
  OleDbCommand com = new OleDbCommand(str, conn);
  com.ExecuteNonQuery(); 这里提示update语句出错

  ...................

请问该怎么该 谢谢


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