string sql = "insert into DEPARTMENT(id,name,commitdate) values(@count,'0',to_date(@dt,'yyyy-mm-dd hh24:mi:ss'))";
                using (OleDbCommand cmd = new OleDbCommand(sql, conn))
                {
                    cmd.Parameters.Add("@dt", OleDbType.VarChar, 50);
                    cmd.Parameters["@dt"].Value =DateTime.Now;    
                    //cmd.Parameters.AddWithValue("@dt",DateTime.Now);//此法也不行

                    cmd.Parameters.Add("@count", OleDbType.VarChar, 50); 
                    cmd.Parameters["@count"].Value = count;//count已赋值
                    if (cmd.ExecuteNonQuery() > 0) //此处已设断点
                    {
                        MessageBox.Show("插入成功");
                        count++;
                    }
                }