How to update the COST column using another table's column

Question

Dear All,
I have table:
table parts: pno, pname, qoh, price, olevel
table orders: ono, cno, eno, received, shipped
table odetails: ono, pno, qty
view:orders_view: ono, cno, eno, received, shipped,sum(qty*price)order_costview:odetails_view: ono, pno, qty, (qty*price)cost
after I update the price in parts, I need to update COST and ORDER_COST too. The orders_view does not have pno, qty, and price, the odetails_view does not have price, how can I update the COST and ORDER_COST. Please help and Thanks in advance!!!
I wrote the update the price in parts:
create or replace procedure change_price(ppno in parts.pno%type, pprice in parts.price%type) as
begin
    update parts
    set price = pprice
    where pno = ppno;
end;
show errorsthis procedure works fine.
I wrote the trigger:
create or replace trigger update_orders_v
after update of price on parts
for each row
begin
    update orders_view
    set order_cost = sum(parts.(:new.price)*parts.qty)
    where parts.pno = :new.pno;
end;
show errorsIt gives me:Errors for TRIGGER UPDATE_ORDERS_V:
LINE/COL ERROR
3/5 PL/SQL SQL Statement ignored
4/22 PL/SQL ORA-00934: group function is not allowed hereplease help!

Answer 1

You could add the columns to the tables and then you would need a trigger to update those columns. However, you could just as easily select the price * qty to get the cost, without creating an additional column or trigger. I have no idea what you might want to do with a global temporary table. I think you need to explain what your purpose is, before any of us can suggest the best method. Since I have already demonstrated an update with a view, I will demonstrate an update with the cost column added to the odetails table and a trigger as you asked about. Notice that you will need triggers on both tables, the one that has qty and the one that has price.
scott@ORA92> create table parts
  2    (pno    number(5) not null primary key,
  3       pname  varchar2(30),
  4       qoh    integer check(qoh >= 0),
  5       price  number(6,2) check(price >= 0.0),
  6       olevel integer)
  7  /
Table created.
scott@ORA92> create table odetails
  2    (ono    number(5),
  3       pno    number(5) references parts,
  4       qty    integer check(qty > 0),
  5       cost   number,
  6       primary key (ono,pno))
  7  /
Table created.
scott@ORA92> create or replace procedure change_price
  2    (ppno   in parts.pno%type,
  3       pprice in parts.price%type)
  4  as
  5  begin
  6    update parts
  7    set    price = pprice
  8    where  pno = ppno;
  9  end;
10  /
Procedure created.
scott@ORA92> create or replace trigger update_cost1
  2    after insert or update of price on parts
  3    for each row
  4  begin
  5    update odetails
  6    set    cost = qty * :new.price
  7    where  pno = :new.pno;
  8  end update_cost1;
  9  /
Trigger created.
scott@ORA92> show errors
No errors.
scott@ORA92> create or replace trigger update_cost2
  2    before insert or update of qty on odetails
  3    for each row
  4  declare
  5    v_price parts.price%type;
  6  begin
  7    select price
  8    into   v_price
  9    from   parts
10    where  pno = :new.pno;
11    --
12    :new.cost := :new.qty * v_price;
13  end update_cost2;
14  /
Trigger created.
scott@ORA92> show errors
No errors.
scott@ORA92> insert into parts values (1, 'name1', 1, 10, 1)
  2  /
1 row created.
scott@ORA92> insert into odetails values (1, 1, 22, null)
  2  /
1 row created.
scott@ORA92> -- starting data:
scott@ORA92> select * from parts
  2  /
       PNO PNAME                                 QOH      PRICE     OLEVEL
         1 name1                                   1         10          1
scott@ORA92> select * from odetails
  2  /
       ONO        PNO        QTY       COST
         1          1         22        220
scott@ORA92> -- update:
scott@ORA92> execute change_price (1, 11)
PL/SQL procedure successfully completed.
scott@ORA92> -- results:
scott@ORA92> select * from parts
  2  /
       PNO PNAME                                 QOH      PRICE     OLEVEL
         1 name1                                   1         11          1
scott@ORA92> select * from odetails
  2  /
       ONO        PNO        QTY       COST
         1          1         22        242
scott@ORA92> -- select works without extra cost column or trigger:
scott@ORA92> select o.ono, o.pno, o.qty, (o.qty * p.price) as cost
  2  from   odetails o, parts p
  3  where  o.pno = p.pno
  4  /
       ONO        PNO        QTY       COST
         1          1         22        242
scott@ORA92>