$query="select * from huge_table where conditions joins etc";
$result=mysql_query($query);
$price_p=array();
$price_s=array();
while($row=mysql_fetch_array($result,MYSQL_ASSOC)){
   if($row['price']=="P"){
       array_push($price_p,$row['price']);
   }
   if($row['price']=="S"){
       array_push($price_s,$row['price']);
   }
}

Select * FROM sales_item d



join (select str_to_date('2007-09-30', '%Y-%m-%d') st_date) v



join item_store f on f.item_no=d.item_no and f.store_id = d.store_id



join item_sellprice_store a on f.item_no=a.item_no and f.store_id = a.store_id



join item b on f.item_no=b.item_no



join item_supplier c on b.item_no=c.item_no and b.supplier_no=c.supplier_no



join item_sellprice_storegroup g on a.batch_id=g.batch_id





join store k on f.store_id =k.store_id



where d.store_id = '011'



and (f.item_status ='A' or f.item_status ='O')



and a.price_type='P'



and a.effective_start_date < v.st_date < a.effective_end_date



and d.sale_date = v.st_date



order by d.category_code, a.sell_gst, a.item_no ;