MySQL Join with sum() - mysql

Question

I have two tables; One contains for products stats and another one contains additional stats
StatsHourly:
id
product_id (can be multiple)
amount
cost
time
StatsValues:
id
product_id (can be multiple)
value (double)
I need to join those two tables and get something like this in the result:
product_id
sum (amount)
sum (cost)
sum (value)
I'm trying to do this:
"SELECT
SUM(s.amount) as amount,
SUM(s.cost) as cost
FROM StatsHourly s
LEFT JOIN (
SELECT
COALESCE(SUM(value), 0) as value
FROM StatsValues
GROUP BY product_id
) value v ON v.product_id = s.product_id
WHERE 1
AND s.product_id = :product_id";
This doesn't work. Could someone show me the right way to do it?

Answer 1

You have an extra comma after as cost:
SUM(s.cost) as cost, <-- here
You also use 2 aliases for the subquery, you should remove value from there:
) value v
You do not use any output from the subquery.
Coalesce() is unnecessary in the subquery.

Answer 2

This works (tested):
SELECT
s.product_id as product_id,
s.amount_s as amount,
s.cost_s as cost,
v.value_v as value
FROM
(SELECT
product_id,
SUM(amount) as amount_s,
SUM(cost) as cost_s
FROM StatsHourly
GROUP BY product_id) as s
LEFT JOIN
(SELECT
product_id,
SUM(value) as value_v
FROM StatsValues
GROUP BY product_id) as v
ON v.product_id = s.product_id;
WHERE s.product_id = 'product_id';
The point is:
As you have multiple equal product_id in BOTH table you have to make two aggregated tables through subqueries that makes the product_id unique and sum all appropriate rows.
After that you can join and you select the already aggregated values.
Regards