Avg details in "matrix" with PL/SQL

Question

Example, I have three tables:
1: manufacturer(id number(20),
name varchar2(36));
2: group(id number(20),
name varchar2(36));
and
3: product(id number(20),
group_id number(20),
manufacturer_id number(20),
name varchar2(36),
price number(10));
Group_id and manufacturer_id are both foreign key to table 1 and
2.
Problem:
I'm wondering if i can execute a SQL statment so i get as an
retun result a matrix of table 1 and 2 with in the matrix the
average prices of each product in that manufacturer, group.
So the first colum of the resultset should contain the name of
the group. And the other colums(as many as there are rows in the
manufacturer table) should contain the average price of the
products by that manufacturer.
I hope i did make my question clear enough to answer it. Thaks in
advance.
Tom

Answer 1

One (admiteedly not very satisfactory) way of doing it is to
hard code the manufacturers i.e.
select group.name
, (sum(decode(product.man_id, 'ABC', product.price,
0))/sum(decode(product.man_id, 'ABC', 1, 0)) AS abc_avg
, (sum(decode(product.man_id, 'DEF', product.price,
0))/sum(decode(product.man_id, 'DEF', 1, 0)) AS def_avg
from group, product
where product.grp_id = group.id
group by group.name
This is only practical when you have a small and static number
of manufacturers. If you have a dynamic Manufacturers table
then I think you'll have to use Oracle Reports, which has a very
good Matrix reporting option, as I don't think you can do this
simply with SQL*Plus.
One option you could try is writing a script that generates the
above code dynamically e.g.
dbms_output.put_line('select group.name');
FOR lrec in (select id, name from manufacturer) LOOP
dbms_output.put_line(',(sum(decode
(product.man_id, '''||lrec.id||''', product.price, 0))/sum(decode
(product.man_id, '''||lrec.id||''', 1, 0))
AS "'||lrec.name||'"');
END LOOP;
dbms_output.put_line('from group, product');
...etc
HTH, APC