SQL - GROUP BY and SUM using joined table fields - mysql

Question

Let's assume there are two different tables:
PACKAGE
id
--
1
2
3
PRODUCT
id | package_id | currency | total
----------------------------------
1 | 1 | USD | 100
2 | 1 | EUR | 200
3 | 2 | USD | 300
4 | 2 | USD | 400
5 | 3 | GBP | 500
And the desired result is to get concatenated total amounts for each package (from its products) by each DISTINCT currency, something like:
id | total_amount
----------------------
1 | USD 100, EUR 200
2 | USD 700
3 | GBP 500
Tried with this query:
SELECT
packages.id,
(
SELECT
GROUP_CONCAT(CONCAT(currency,' ',total))
FROM
(
SELECT
products.currency AS currency,
SUM(products.total) AS total
FROM products
WHERE products.package_id = [[ packages.id ]] -- double brackets just for marking
GROUP BY products.currency
) T
) AS total_amount
FROM packages
LEFT JOIN products
ON products.package_id = packages.id
GROUP BY packages.id;
But there is an error that package.id (in double brackets above) is not visible, probably because of the subquery depth.
Is there any way that it can be achieved? Thanks.

Answer 1

You may try rewriting your query as a left join instead of a subquery which may be more efficient or faster as shown below:
SELECT
p.id,
ct.currency_totals
FROM
packages p
LEFT JOIN (
SELECT
package_id,
GROUP_CONCAT(
CONCAT(currency,' ',total)
) as currency_totals
FROM (
SELECT
package_id,
currency,
SUM(total) as total
FROM
products
GROUP BY
package_id,
currency
) t
GROUP BY
package_id
) ct on ct.package_id=p.id;
id
currency_totals
1
USD 100,EUR 200
2
USD 700
3
GBP 500
Moreover, if you only require the package id of currently used packages and no other details , using your subquery may be enough for this task.
SELECT
package_id,
GROUP_CONCAT(
CONCAT(currency,' ',total)
) as currency_totals
FROM (
SELECT
package_id,
currency,
SUM(total) as total
FROM
products
GROUP BY
package_id,
currency
) t
GROUP BY
package_id;
package_id
currency_totals
1
USD 100,EUR 200
2
USD 700
3
GBP 500
View working demo on DB Fiddle

Answer 2

you can use :
select package_id , group_concat(concat(currency,' ',grandtotal))
from (
select package_id,currency, sum(total) grandtotal
from products
group by package_id,currency
) t group by package_id
db<>fiddle here

Answer 3

Try use alias for tables names to identify...
SELECT
pkg.id,
(
SELECT
GROUP_CONCAT(CONCAT(currency,' ',total))
FROM
(
SELECT
products.currency AS currency,
SUM(products.total) AS total
FROM products
WHERE products.package_id = pkg.id
GROUP BY products.currency
) T
) AS total_amount
FROM packages as pkg
LEFT JOIN products
ON products.package_id = pkg.id
GROUP BY pkg.id;