使用NPOI，完成数据的导入导出

解释下流程，第一步：将数据库表中的数据导出到excel表
                          第二步：将excel表中的数据再插入到数据库表中（当然没有做重复性校验，测试而已）
注：表结构很简单：
　　Id (int) 自增
　　Name (nvarchar(20))
　　Age (int)
　　Phone(nvarchar(13))

 class Program
    {
        /* 首先用ado.net简单封装下 Insert和Select操作，导入导出要用到*/

        //封装ado.net  Insert操作
        static void Insert(string sql, params SqlParameter[] parameters)
        {
            string connstr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    cmd.ExecuteNonQuery();
                }
            }
        }

        //封装ado.net Select操作
        static DataTable Select(string sql, params SqlParameter[] parameters)
        {
            DataTable table = new DataTable();
            string connstr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    using (SqlDataReader read = cmd.ExecuteReader())
                    {
                        table.Load(read);
                    }
                }
            }
            return table;
        }
    
        /*封装导入导出方法*/

        //从数据库表中导出数据到excel表中
        static void Export_toxlsx()
        {
            IWorkbook wb = new XSSFWorkbook();
            ISheet sheet =  wb.CreateSheet("sheet1");  //创建工作簿“sheet1”
           /*表头*/
           IRow title =  sheet.CreateRow(0);
            ICell cell_0 = title.CreateCell(0);
            cell_0.SetCellValue("姓名");
            ICell cell_1 = title.CreateCell(1);
            cell_1.SetCellValue("年龄");
            ICell cell_2 = title.CreateCell(2);
            cell_2.SetCellValue("电话");
            /*表内容*/
            DataTable tb = Select("select * from t_test");
            int i = 1;
            foreach(DataRow item in tb.Rows)
            {
                IRow row = sheet.CreateRow(i);
                ICell cell0 = row.CreateCell(0);
                cell0.SetCellValue((string)item["Name"]);
                ICell cell1 = row.CreateCell(1);
                cell1.SetCellValue((int)item["Age"]);
                ICell cell2 = row.CreateCell(2);
                cell2.SetCellValue((string)item["Phone"]);
                i++;
            }

            using (Stream stream = File.OpenWrite(@"e:/test/test.xlsx"))
            {
                wb.Write(stream); //将使用npoi创建的xlsx文件写入到流中
            }
            Console.WriteLine("Export Done!");
        }
        //从excel表中将数据导入到数据库中
        static void Import_toDb()
        {
            IWorkbook wb = WorkbookFactory.Create(@"e:/test/test.xlsx");
            ISheet sheet = wb.GetSheetAt(0); //获取test.xlsx的第一个工作簿

            for(int i=1; i<=sheet.LastRowNum;i++) //从第一行开始读，第0行为表头
            {
                IRow row = sheet.GetRow(i);
                ICell cell_0 = row.GetCell(0);
                ICell cell_1 = row.GetCell(1);
                ICell cell_2 = row.GetCell(2);

                Insert("insert into t_test (Name,Age,Phone) values(@Name,@Age,@Phone)",
                    new SqlParameter("@Name",cell_0.StringCellValue),
                    new SqlParameter("@Age",(int)cell_1.NumericCellValue),
                    new SqlParameter("@Phone",cell_2.StringCellValue));
            }
            Console.WriteLine("Inset Done!");
        }
        static void Main(string[] args)
        {
           
            Export_toxlsx();
            Import_toDb();
            Console.ReadKey();
        }

    }