NPOI导入数据库

 OpenFileDialog filedialog = new OpenFileDialog();
            filedialog.Filter = "Excel文件|*.xls";
            if (filedialog.ShowDialog() != DialogResult.OK)
            {
                return;
            }
            string filename = filedialog.FileName;
            using (FileStream fs = File.OpenRead(filename))
            {
                IWorkbook workbook = new HSSFWorkbook(fs);
                ISheet sheet = workbook.GetSheetAt(0);
                string sql = "insert into information values (@cityname,@hotelname,@postion)";
                using (SqlConnection conn = new SqlConnection(conStr))
                {
                    using (SqlCommand cmd = new SqlCommand(sql, conn))
                    {
                        SqlParameter[] paras = { 
                                               new SqlParameter("@cityname",SqlDbType.NVarChar),
                                               new SqlParameter("@hotelname",SqlDbType.NVarChar),
                                               new SqlParameter("@postion",SqlDbType.NVarChar)
                                               };
                        for (int i = 1; i < sheet.LastRowNum; i++)
                        {
                            IRow row = sheet.GetRow(i);
                            for (int j = 0; j < 3; j++)
                            {
                                if (row.GetCell(j) == null)
                                {
                                    paras[j].Value = "空";
                                  
                                }
                                else
                                {
                                    paras[j].Value = row.GetCell(j).ToString();
                                   
                                } 
                              
                            }
                            cmd.Parameters.AddRange(paras);
                            conn.Open();
                            cmd.ExecuteNonQuery();
                            cmd.Parameters.Clear();//不写这里会报错
                            conn.Close();
                        }
                    }
                }
            }
            MessageBox.Show("OK");
        }