Notes

protected void GetExcel_Click(object sender, EventArgs e)
{
// Create a DataTable to hold your data (you can replace this with your actual data)
DataTable dataTable = new DataTable();

foreach (DataControlFieldHeaderCell headerCell in GridView1.HeaderRow.Cells)
{
dataTable.Columns.Add(headerCell.Text);
}

foreach (GridViewRow row in GridView1.Rows)
{
DataRow dataRow = dataTable.NewRow();
for (int i = 0; i < row.Cells.Count; i++)
{
dataRow[i] = row.Cells[i].Text;
}
dataTable.Rows.Add(dataRow);
}

// Export DataTable to Excel
if (dataTable != null && dataTable.Rows.Count > 0)
{
// Generate Excel content and save it to a memory stream
using (var package = new ExcelPackage())
{
var worksheet = package.Workbook.Worksheets.Add("Sheet1");
worksheet.Cells["A1"].LoadFromDataTable(dataTable, true);
worksheet.Cells[worksheet.Dimension.Address].AutoFitColumns();

// Specify the custom file name (you can modify this as needed)
string customFileName = "exported_data_" + DateTime.Now.ToString("yyyyMMddHHmmss") + ".xlsx";

// Save the Excel package to a memory stream
byte[] fileBytes = package.GetAsByteArray();

// Set the content type and headers for the response
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AppendHeader("Content-Disposition", "attachment; filename=" + customFileName);

// Write the file bytes to the response stream
Response.BinaryWrite(fileBytes);
Response.Flush();
Response.End();

Label16.Visible = true;
Label16.Text = customFileName + " нэртэй excel file амжилттай татагдлаа!";
}
}
else
{
// Handle the case where the DataTable is empty or null
// You can show a message to the user or take appropriate action
}
}