Hi can i ask some help how can i sum the amount and group by manufacturer

and i want only to sum if the order_id is equal to 0001
if i have this tables

product_group
Code:
    prod_code        productname           manufacturer                   manuf_code
  
    A001                       laptop                 samsung                         001
    B002                      mouse                  Neo                                005
    A002                      monitor(LED)         samsung                          001
    B001                      keyboard              hp                                  003

orderdetail

Code:
  order_id        ord_prodcode           ord_desc                         invqty            price           amount
   0001            A001                      laptop                                5                   100             500
   0001            B002                      mouse                               2                      50            100
  0001             A002                      monitor(LED)                      5                   250             1250
  0004            B001                      keyboard                             5                  25                125

orderheader

Code:
   orderdate            order_id
   10-12-13            0001
    10-12-13           0001
   10-12-13            0001
   9-12-13             0001
I dont have idea on how to do this in php,,I hope you can help me thank you in advance.