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How to export excel from dataset or datatable in c#?
using Excel = Microsoft.Office.Interop.Excel;
 public static bool ExportDataTableToExcel(DataTable dt, string filepath)
    {

    Excel.Application oXL;
    Excel.Workbook oWB;
    Excel.Worksheet oSheet;
    Excel.Range oRange;

    try
    {
        // Start Excel and get Application object.
        oXL = new Excel.Application();

        // Set some properties
        oXL.Visible = true;
        oXL.DisplayAlerts = false;

        // Get a new workbook.
        oWB = oXL.Workbooks.Add(Missing.Value);

        // Get the Active sheet
        oSheet = (Excel.Worksheet)oWB.ActiveSheet;
        oSheet.Name = "Data";

        int rowCount = 1;
        foreach (DataRow dr in dt.Rows)
        {
            rowCount += 1;
            for (int i = 1; i < dt.Columns.Count + 1; i++)
            {
                // Add the header the first time through
                if (rowCount == 2)
                {
                    oSheet.Cells[1, i] = dt.Columns[i - 1].ColumnName;
                }
                oSheet.Cells[rowCount, i] = dr[i - 1].ToString();
            }
        }

        // Resize the columns
        oRange = oSheet.get_Range(oSheet.Cells[1, 1],
                      oSheet.Cells[rowCount, dt.Columns.Count]);
        oRange.EntireColumn.AutoFit();

        // Save the sheet and close
        oSheet = null;
        oRange = null;
        oWB.SaveAs(filepath, Excel.XlFileFormat.xlWorkbookNormal,
            Missing.Value, Missing.Value, Missing.Value, Missing.Value,
            Excel.XlSaveAsAccessMode.xlExclusive,
            Missing.Value, Missing.Value, Missing.Value,
            Missing.Value, Missing.Value);
        oWB.Close(Missing.Value, Missing.Value, Missing.Value);
        oWB = null;
        oXL.Quit();
    }
    catch
    {
        throw;
    }
    finally
    {
        // Clean up
        // NOTE: When in release mode, this does the trick
        GC.WaitForPendingFinalizers();
        GC.Collect();
        GC.WaitForPendingFinalizers();
        GC.Collect();
    }

    return true;
}

private void DumpExcel(DataTable tbl)
{
    using (ExcelPackage pck = new ExcelPackage())
    {
            //Create the worksheet
            ExcelWorksheet ws = pck.Workbook.Worksheets.Add("Demo");

            //Load the datatable into the sheet, starting from cell A1. Print the column names on row 1
            ws.Cells["A1"].LoadFromDataTable(tbl, true);

            //Format the header for column 1-3
            using (ExcelRange rng = ws.Cells["A1:C1"])
            {
                rng.Style.Font.Bold = true;
                rng.Style.Fill.PatternType = ExcelFillStyle.Solid;                      //Set Pattern for the background to Solid
                rng.Style.Fill.BackgroundColor.SetColor(Color.FromArgb(79, 129, 189));  //Set color to dark blue
                rng.Style.Font.Color.SetColor(Color.White);
            }

            //Example how to Format Column 1 as numeric
            using (ExcelRange col = ws.Cells[2, 1, 2 + tbl.Rows.Count, 1])
            {
                    col.Style.Numberformat.Format = "#,##0.00";
                    col.Style.HorizontalAlignment = ExcelHorizontalAlignment.Right;
                }

                //Write it back to the client
                Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                Response.AddHeader("content-disposition", "attachment;  filename=ExcelDemo.xlsx");
                Response.BinaryWrite(pck.GetAsByteArray());
            }
        }
    }
}

using Microsoft.Office.Interop.Excel;