complex sql query (GROUP BY) - mysql

Question

I need some help building a query.
Here is what I need :
I have a table called data:
ID| PRODUCT | VALUE |COUNTRY| DEVICE | SYSTEM
-----+---------+-------+-------+---------+--------
48 | p1 | 0.4 | US | dev1 | system1
47 | p2 | 0.67 | IT | dev2 | system2
46 | p3 | 1.2 | GB | dev3 | system3
45 | p1 | 0.9 | ES | dev4 | system4
44 | p1 | 0.6 | ES | dev4 | system1
I need to show which products have produced the most revenue and which country, device and system contributed the most.
**for example : the result i would get from the table would be:
PRODUCT | TOTAL COST |COUNTRY| DEVICE | SYSTEM
-------+------------+-------+---------+--------
p1 | 1.9 | ES | dev4 | system1
p2 | 0.67 | IT | dev2 | system2
p3 | 1.2 | GB | dev3 | system3
Top country is ES because ES contributed with 0.9 + 0.6 = 1.5 > 0.4 (contribution of US).
same logic for top device and top system.**
I guess for total revenue and product something like this will do :
SELECT SUM(value) as total_revenue,product FROM data GROUP BY product
But how can I add country,device and system?
Is this even feasible in a single query, if not what is the best way (performance wise) to do it?
Many thanks for your help.
EDIT
I edited the sample table to explain better.

Answer 1

Do it in separate queries:
SELECT product,
SUM(value) AS amount
FROM data
GROUP BY country -- change to device, system, etc. as required
ORDER BY amount DESC
LIMIT 1

Answer 2

You are correct... it is not just a simple query... but 3 queries wrapped into one result.
I've posted my sample out on SQL Fiddle here...
First query -- the inner most. You need to get all revenue based on a per product/country and sort that by the product and DESCENDING on the total revenue to have highest revenue in first position per product.
Next query (where I've implemented use of MySQL #variable use). Since the first result order already has it in order of product and revenue rank, I set the rank to 1 every time a product changes from whatever the "#LastProd" is... This would create ES = Rank #1 for product 1, then US = Rank #2 for product 1, then continue on the other "products".
The final outermost query re-joins back to the raw Data table but gets a list of all the devices and systems that comprised the product sale in question, but ONLY where the product rank was #1.
select
pqRank.product,
pqRank.country,
pqRank.revenue,
group_concat( distinct d2.device ) as PartDevices,
group_concat( distinct d2.system ) as PartSystems
from
( select
pq.product,
pq.country,
pq.revenue,
#RevenueRank := if( #LastProd = pq.product, #RevenueRank +1, 1 ) as ProdRank,
#LastProd := pq.product
from
( select
d.product,
d.country,
sum( d.value ) as Revenue
from
data d
group by
d.product,
d.country
order by
d.product,
Revenue desc ) pq,
( select #RevenueRank := 0,
#LastProd := ' ') as sqlvars
) pqRank
JOIN data d2
on pqRank.product = d2.product
and pqRank.country = d2.country
where
pqRank.ProdRank = 1
group by
pqRank.product,
pqRank.country

Answer 3

You could do sth like that
CREATE TABLE data
(
id int auto_increment primary key,
product varchar(20),
country varchar(4),
device varchar(20),
system varchar(20),
value decimal(5,2)
);
INSERT INTO data (product, country, device, system, value)
VALUES
('p1', 'US', 'dev1', 'system1', 0.4),
('p2', 'IT', 'dev2', 'system2', 0.67),
('p1', 'IT', 'dev1', 'system2', 0.23);
select 'p' as grouping_type, product, sum(value) as sumval
from data
group by product
union all
select 'c' as grouping_type, country, sum(value) as sumval
from data
group by country
union all
select 'd' as grouping_type, device, sum(value) as sumval
from data
group by device
union all
select 's' as grouping_type, system, sum(value) as sumval
from data
group by system
order by grouping_type, sumval
It's ugly, I wouldn't use it, but it should work.