how to export sql datatable into excel sheet using c#?

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C#

i have developed a software to export a excel sheet by clicking menuitem.

so now i want to get column name as well. but this will show only column data?
What i have to do?

private void exportEnquiryToolStripMenuItem_Click(object sender, EventArgs e)
        {

            SqlConnection cnn;
            string connectionstring = null;
            string sql = null;
            string data = null;
            int i = 0;
            int j = 0;
 
            Excel.Application xlApp;
            Excel.Workbook xlWorkBook;
            Excel.Worksheet xlWorkSheet;
            object misValue = System.Reflection.Missing.Value;
 
 
            xlApp = new Microsoft.Office.Interop.Excel.Application();
            xlWorkBook = xlApp.Workbooks.Add(misValue);
            xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

            connectionstring = "Data Source=PD-JANAKAN;Initial Catalog=EnqInfo;Integrated Security=True";
            cnn = new SqlConnection(connectionstring);
            cnn.Open();
            sql = "SELECT * FROM Enquiry";
            SqlDataAdapter dscmd = new SqlDataAdapter(sql, cnn);
            DataSet ds = new DataSet();
            dscmd.Fill(ds);

           
 
            for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
            {
                for (j = 0; j <= ds.Tables[0].Columns.Count - 1; j++)
                {
                    data = ds.Tables[0].Rows[i].ItemArray[j].ToString();
                    xlWorkSheet.Cells[i + 1, j + 1] = data;
                }
            }


            xlWorkBook.SaveAs("D:\\informations.xls", Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
            xlWorkBook.Close(true, misValue, misValue);
            xlApp.Quit();
 
            releaseObject(xlWorkSheet);
            releaseObject(xlWorkBook);
            releaseObject(xlApp);
 
 
            MessageBox.Show("Excel file created , you can find the file D:\\Sam-informations.xls");
        }
 
        private void releaseObject(object obj)
        {
            try
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
                obj = null;
            }
            catch (Exception ex)
            {
                obj = null;
                MessageBox.Show("Exception Occured while releasing object " + ex.ToString());
            }
            finally
            {
                GC.Collect();
            }
 
        }

        }