NPOI导入，导出数据库

<pre name="code" class="csharp">using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace 将excel数据插入数据库
{
class Program
{
private static readonly string str = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
static void Main(string[] args)
{
//导入数据库
using (FileStream stream = new FileStream("C:/Users/dong/Desktop/1234.xls", FileMode.Open, FileAccess.Read))
{
HSSFWorkbook work = new HSSFWorkbook(stream);
ISheet sheet = work.GetSheetAt(0);  //注意当是导入的时候用GetSheetAt(0);，导出的时候.CreateSheet("员工数据");

DataTable table = new DataTable(); //创建以个Datatable对象

table.Columns.Add("Name", typeof(string));

int num = sheet.LastRowNum;
for (int i = 1; i <= num; i++)
{
IRow row = sheet.GetRow(i);   //创建行
DataRow daterow = table.NewRow();
for (int j = 1; j < row.LastCellNum; j++)
{
daterow["Name"] = row.GetCell(j).StringCellValue;
table.Rows.Add(daterow);
}

//Student stu = new Student();
//stu.Name = row.GetCell(1).StringCellValue;
//SqlHelper.ExecuteNonQuery("insert into T_Excel(Name) values(@Name)",
//                                       new SqlParameter("@Name", stu.Name));

}

using (SqlBulkCopy bulk = new SqlBulkCopy(str))
{
bulk.DestinationTableName = "T_Excel";
bulk.ColumnMappings.Add("Name", "Name");
bulk.WriteToServer(table);
}
}

//导出数据库
List<Student> list = new List<Student>();
DataTable dt= SqlHelper.ExecuteDataTable("select * from T_Excel");
if (dt.Rows.Count > 0)
{
foreach (DataRow dr in dt.Rows)
{
list.Add(RowToModel(dr));
}
}
using (FileStream stream = new FileStream("C:/Users/dong/Desktop/导出.xls", FileMode.Create, FileAccess.Write))
{
HSSFWorkbook work = new HSSFWorkbook();
ISheet sheet = work.CreateSheet("员工数据");
IRow row = sheet.CreateRow(0);
row.CreateCell(0, CellType.NUMERIC).SetCellValue("编号");
row.CreateCell(1, CellType.NUMERIC).SetCellValue("姓名");
row.CreateCell(2, CellType.NUMERIC).SetCellValue("入职日期");
for (int i = 0; i <list.Count; i++)
{
Student stu = list[i];
IRow irow = sheet.CreateRow(i+1);
irow.CreateCell(0, CellType.STRING).SetCellValue(stu.Id);
irow.CreateCell(1, CellType.STRING).SetCellValue(stu.Name);

//下面是日期类型的处理
ICellStyle style = work.CreateCellStyle();
IDataFormat format = work.CreateDataFormat();

style.DataFormat = format.GetFormat("yyyy\"年\"m\"月\"d\"日\"");
ICell cellInDate = irow.CreateCell(2,CellType.NUMERIC);
cellInDate.CellStyle = style;
cellInDate.SetCellValue(stu.Time);
}
work.Write(stream);
}
}

public static Student RowToModel(DataRow dr)
{
Student s = new Student();
s.Id=(long)dr["Id"];
s.Name=(string)dr["Name"];
s.Time=(DateTime)dr["Time"];
return s;
}
}
}

当从数据库导出的时候，是已知数据，创建excel表，所以用到CreateSheet，CreateRow等。

当从excel导入数据库的时候，用到GetSheet，GetRow等。

日期类型的数据处理有些特殊，在代码中可以看出