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实现过程： 要导出来的数据库数据量很大，一次取出来压力有点大，故分批取出来，导入到同一个Excel。 因为Excel2003版最大行数是65536行，Excel2007开始的版本最大行数是1048576行，故NPOI导出时候选择了Excel2007。

Form1.cs

/*引用命名空间：using System.IO;using System.Threading.Tasks;using NPOI.HSSF.UserModel;using NPOI.SS.UserModel;using NPOI.XSSF.UserModel;*/      public Form1(){    InitializeComponent();    List
   
     list = new List
    
     (){          new DictionaryEntry(1, "XA"),          new DictionaryEntry(2, "XB")    };    cbType.BindComboBox(list);                    }private void CreateExcel(string fileName){    if (File.Exists(fileName))        File.Delete(fileName);    IWorkbook workbook = new XSSFWorkbook();    ISheet sheet = workbook.CreateSheet("Sheet1");    FileStream sw = File.Create(fileName);    workbook.Write(sw);    sw.Close();                   }private void btnExport_Click(object sender, EventArgs e){                try    {        Task.Factory.StartNew(() =>        {            txtSql.SafeCall(() =>            {                txtSql.AppendText("开始处理...\r\n");            });            BusinessType businessType = GetBusinessType();            string[] sqlWhereArray = Sql.SqlWhereArray;            string[] DateRemarkArray = Sql.DateRemarkArray;            string fileName = string.Format("{0}.xlsx", businessType.ToString());            CreateExcel(fileName);                                                   string sqlCount = Sql.GetRecordSql(businessType, "");            int recordCount = db.ExecuteScalar(sqlCount);               int sqlIndex = 0;            int rowIndex = 0;            foreach (string sqlWhre in sqlWhereArray)                                {                sqlIndex++;                FileStream fs = File.Open(fileName, FileMode.Open);                  IWorkbook workbook = new XSSFWorkbook(fs);                                      ISheet sheet = workbook.GetSheetAt(0);                txtSql.SafeCall(() =>                {                    txtSql.AppendText("条件" + sqlIndex.ToString() + "：" + DateRemarkArray[sqlIndex - 1]);                });                string sql = Sql.GetDataSql(businessType, sqlWhre);                DataTable dt = db.GetDataSet(sql).Tables[0];                int columnsCount = dt.Columns.Count;                if (sqlIndex == 1)                {                    IRow row0 = sheet.CreateRow(0);                                                for (int m = 0; m < columnsCount; m++)                    {                        DataColumn dc = dt.Columns[m];                        row0.CreateCell(m).SetCellValue(dc.ColumnName);                    }                }                for (int i = 0; i < dt.Rows.Count; i++)                {                    rowIndex++;                    DataRow dr = dt.Rows[i];                                            IRow row = sheet.CreateRow(rowIndex);                    for (int j = 0; j < columnsCount; j++)                    {                        row.CreateCell(j).SetCellValue(dr[j].ToString());                    }                    lblMsg.SafeCall(() =>                    {                        if(i == (dt.Rows.Count - 1))                            txtSql.AppendText(" 行数：" + (i+1).ToString() + "\r\n");                        lblMsg.Text = string.Format("正在导出第{0}个条件，第{1}行", sqlIndex.ToString(), (i + 1).ToString());                        double x = rowIndex * 1.0 / recordCount * 100;                        lblProgress.Text = string.Format("总行数：{0}, 当前完成总{1}行，百分占比：{2} %", recordCount.ToString(), rowIndex.ToString(), x.ToString("#0.0"));                    });                }                FileStream outFs = new FileStream(fileName, FileMode.Open);                workbook.Write(outFs);                outFs.Close();            }                           }).ContinueWith(TaskEnded);    }    catch (Exception ex)    {        MessageBox.Show("发生异常，错误提示：" + ex.Message);    }}private void TaskEnded(Task task){    txtSql.SafeCall(() =>    {        lblMsg.Text = "全部导出完成！";        txtSql.AppendText("处理完成！\r\n");                   });}
    
   

Extensions.cs

public static class Extensions{    public static void SafeCall(this Control ctrl, Action callback)    {        if (ctrl.InvokeRequired)            ctrl.Invoke(callback);        else            callback();    }    public static void BindComboBox(this ComboBox cb, List
   
     list)    {        cb.DisplayMember = "Value";        cb.ValueMember = "Key";        cb.DataSource = list;    }}
   

Sql.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace DataExport{    public enum BusinessType    {        XA = 1,        XB = 2    }    public class Sql    {        /// 
        /// 分批获取sql的where条件        /// 
        public static string[] SqlWhereArray = {                                  " 条件1 ",                                 " 条件2 ",                                 " 条件3 "                                 };                /// 
        /// sql的where条件说明        /// 
        public static string[] DateRemarkArray = {                              "20130101至20130331",                            "20130401至20130630",			    "20130701后",                             };        /// 
        /// 获取sql语句        /// 
        ///         ///         ///         /// 
           private static string GetSql(BusinessType type, string columns, string sqlWhere)        {            string sql = "";            switch (type)            {                case BusinessType.XA:                    sql = string.Format(@"SELECT {0}  FROMM tb1 WHERE 1=1 {1} ", columns, sqlWhere);                    break;                case BusinessType.XB:                    sql = string.Format(@"SELECT {0}  FROMM tb2 WHERE 1=1 {1} ", columns, sqlWhere);                    break;            }            return sql;        }        /// 
        /// 获取总记录数        /// 
        ///         ///         /// 
           public static string GetRecordSql(BusinessType type, string sqlWhere)        {            string columns = "count(*)";            return GetSql(type, columns, sqlWhere);        }        /// 
        /// 获取数据        /// 
        ///         ///         /// 
           public static string GetDataSql(BusinessType type, string sqlWhere)        {            string columns = "";            switch (type)            {                case BusinessType.XA:                                columns = @"                                col1 列1,				col2 列2,                                col3 列3                                 ";                    break;                case BusinessType.XB:                                columns = @"                                col1 列1,				col2 列2                                 ";                    break;                                   }            return GetSql(type, columns, sqlWhere);       }    }}

备注：

NPOI组件下载：

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另外，NPOI只有 2.0以上版本才支持Excel 2007，用法

//自动辨别2007或2003 IWorkbook workbook = WorkbookFactory.Create(FileUpload1.FileContent); //2007 XSSFWorkbook workbook = new XSSFWorkbook(FileUpload1.FileContent); //2003 HSSFWorkbook workbook = new HSSFWorkbook(FileUpload1.FileContent);

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