จะ insert ข้อมูลจากตารางที่ union กัน 3 ตาราง ไปลงอีก ตารางหนึ่ง ใน Database ทำไงครับ

// Invoice Detail
$sql= " (select webreg__tax_invoice_item.description
       ,webreg__tax_invoice_item.unit_amount,webreg__tax_invoice_item.amount
       from webreg__pending_order,webreg__tax_invoice_item
       where  webreg__pending_order.invoice_item_id = webreg__tax_invoice_item.id
       and webreg__pending_order.username='$bp' and webreg__pending_order.status='Approve'
       and (date(webreg__pending_order.process_date) between '$date1' and '$date2')
       order by webreg__pending_order.process_date )
       
       UNION ALL
       
       ( select webreg__tax_invoice_item.description
       ,webreg__tax_invoice_item.unit_amount,webreg__tax_invoice_item.amount
       from webreg__pending_renew,webreg__tax_invoice_item
       where webreg__pending_renew.invoice_item_id = webreg__tax_invoice_item.id
       and webreg__pending_renew.username='$bp' and webreg__pending_renew.status='Approve'
       and (date(webreg__pending_renew.process_date) between '$date1' and '$date2')
       order by webreg__pending_renew.process_date  )
       
       UNION ALL
       
      ( select webreg__tax_invoice_item.description,webreg__tax_invoice_item.unit_amount
      ,webreg__tax_invoice_item.amount
       from webreg__pending_transfer_in,webreg__tax_invoice_item
       where webreg__pending_transfer_in.invoice_item_id = webreg__tax_invoice_item.id
       and webreg__pending_transfer_in.username='$bp' and webreg__pending_transfer_in.status='Approve'
       and (date(webreg__pending_transfer_in.process_date) between '$date1' and '$date2')
       order by webreg__pending_transfer_in.process_date)
      LIMIT $Page_Start,$Per_Page";


while($rows=mysql_fetch_array($result))
{
   
    echo"<tr><td>".$i."</td><td>".$rows['description']."</td><td>".$rows['unit_amount']."</td></tr>";
  $i++;