ASP.NET

<asp:BoundColumn DataField="RegistrationDate" HeaderText="Reg Date" SortExpression="RegistrationDate" DataFormatString="{0:yyyy/mmm/dd}">
<HeaderStyle Font-Bold="True" Wrap="False"></HeaderStyle>
<ItemStyle Wrap="False"></ItemStyle>
</asp:BoundColumn>

DataSet ds = CandidateManager.getCandidateDetails(cboStatus.SelectedValue, cboLocation.SelectedItem.Text.Trim(),cboType.SelectedItem.Text.Trim(),txtName.Text.Trim(),txtCurrentOrg.Text.Trim(),txtRegFromDate.Text.Trim(),txtRegToDate.Text.Trim(),m_summaryDetails);
			DataView Source = ds.Tables["CANDIDATE_MASTER"].DefaultView;
			Source.Sort = e.SortExpression;
			Session["Candidate_Sort"] = e.SortExpression;
			DGInbox.DataSource = Source;
			DGInbox.DataBind();

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Xml.Xsl;
using System.Text;
using System.Threading;

/// <summary>
/// Summary description for ExportToExcel
/// </summary>
public class ExportToExcel
{
	System.Web.UI.Page  page;
	System.Web.HttpResponse Response;

	public ExportToExcel(System.Web.UI.Page page)
	{
		page = this.page;
		Response = System.Web.HttpContext.Current.Response;

	}
	public void ExportDataToExcel(DataTable datatable, string[] Headers, string SourcePath, string DestinationPath)
	{
		int i, j;
		string strSourceTemplate = "";
		string strDestFileName = "";
		string strHeaders = "";
		string strRow = "";
      
		System.Data.OleDb.OleDbConnection objXlsCon = null;
		System.Data.OleDb.OleDbCommand objCmd;

		try
		{
			objXlsCon = new System.Data.OleDb.OleDbConnection();
//			if (Headers.Length != datatable.Columns.Count)
//			{
//				throw new Exception("Export Headers List and Table columns should be of same length");
//			}
			if (datatable.Rows.Count > 0)
			{
				strSourceTemplate = SourcePath;
				strDestFileName = DestinationPath;
				//if (File.Exists(strDestFileName))
				//{
				//    File.Delete(strDestFileName);
				//}
				System.IO.File.Copy(strSourceTemplate, strDestFileName);

				objXlsCon.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + strDestFileName + ";Extended Properties=\"Excel 8.0;HDR=Yes;MAXSCANROWS=1;\";";
				objXlsCon.Open();
				objCmd = new System.Data.OleDb.OleDbCommand();
				objCmd.Connection = objXlsCon;

				//getting template headers
				for (i = 0; i < Headers.Length; i++)
				{
					strHeaders += Headers[i].ToString() + ",";
				}
				string s=datatable.Columns[0].ColumnName;
				int k=0;
				//getting values 
				foreach (DataRow drow in datatable.Rows)
				{
					for (j = 0; j < datatable.Columns.Count; j++)
					{
						
						//if(Headers.Length > k)
						//if(drow[j].ToString() != "" && drow[j].ToString().Length<255)
						if(Headers.Length > k)
						{
							if(datatable.Columns[j].ColumnName == Headers[k].ToString())
							{
								if(drow[j].ToString() != "" )//&& drow[j].ToString().Length<255)
								{
									strRow += drow[j].ToString() + "','";
									
								}
								else
								{
									//							if(datatable.Columns[j].DataType.FullName == "System.String" || datatable.Columns[j].DataType.FullName == "System.DateTime")
									strRow +="-'"+",'";
									//							else
									//								strRow +="0"+",";

								}
								k++;
							}
							//k++;
						}
					}
                   
					objCmd.CommandText = "Insert into [Sheet1$] (" + strHeaders.Substring(0, strHeaders.Length - 1) + ") values ('" + strRow.Substring(0, strRow.Length - 3) + "')";
					objCmd.ExecuteNonQuery();
					strRow = "";
					j = 0;
					k=0;
				}

			}
		}
		catch (Exception ex)
		{
			throw ex;
		}
		finally
		{
			objCmd = null;
			objXlsCon.Close();
		}
       
	}
	public void Download(string strFileName, string SourceFolder)
	{
		string path = SourceFolder;
		Response.AddHeader("Content-Disposition", "attachment; filename=" + strFileName + ".xls");
		Response.ContentType = "application/ms-excel";
		FileStream fs = null;
		fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
		byte[] data = new byte[fs.Length];
		fs.Read(data, 0, (int)fs.Length);
		fs.Close();
		Response.BinaryWrite(data);

		Response.End();

	}

}