Get sold products within date range and order them by sold quantity

Question

I have this table scheme (removed non-important columns):

and I am programming REST API on that. I need to get paginated products sold within some date range.

This wouldn't be a problem for me, but I also need to sort them by either product's code or its sold quantity. The latter is a problem for me.

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My idea was to query products and then use subquery to find their sold_products filtered by date and sum the resulting sold quantities. Then order by that sum.

This works but this really is not efficient. For every single product I have to sum it's sold products and in the end I only take 10 results (because I'm using pagination). My latest attempt using this way took 6.5 seconds, so...

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My second idea was to go from the other side. Query sold_products, group them by product_id , filter them and then find it's parents.

This works well, this would be exactly it, but there is one problem - I don't get products which were not sold yet.

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How can I do this? I think I won't need exact query, just some idea how should I approach this should be enough.

Thank you in advance!

EDIT:

Input data in CSV (hope it's ok like this):

product:

id	code
1	A11
2	A12
3	B11

product_variant:

id	product_id	code	initial_quantity
1	1	A11-1	50
2	1	A11-2	50
3	1	A11-3	80
4	2	A12-1	20
5	2	A12-2	30
6	2	A12-3	80
7	2	A12-4	90
8	3	B11-1	70
9	3	B11-2	70

sold_product:

id	product_id	product_variant	quantity	date
1	1	1	20	2021-04-01
2	1	1	15	2021-04-01
3	1	2	15	2021-04-04
4	1	3	10	2021-04-05
5	1	3	19	2021-04-07
6	2	4	11	2021-04-07
7	2	5	12	2021-04-08
8	2	7	15	2021-04-10
9	2	7	15	2021-04-10

Result:

product_id	product_code	initial_quantity	sold_quantity
1	A11	180	79
2	A12	220	53
3	B11	140	0 or NULL

Result when sold date range 2021-04-07 to 2021-04-08 and ordered by sold_quantity asc:

product_id	product_code	initial_quantity	sold_quantity
3	B11	140	0 or NULL
1	A11	180	19
2	A12	220	23

Sample data SQL:

CREATE TABLE product(id INT, code VARCHAR(25));
CREATE TABLE product_variant(id INT, product_id INT, code VARCHAR(25), initial_quantity INT);
CREATE TABLE sold_product(id INT, product_id INT, product_variant_id INT, quantity INT, date_time DATETIME);

INSERT INTO product VALUES(1,'A11');
INSERT INTO product VALUES(2,'A12');
INSERT INTO product VALUES(3,'B11');

INSERT INTO product_variant VALUES(1,1,'A11-1',50);
INSERT INTO product_variant VALUES(2,1,'A11-2',50);
INSERT INTO product_variant VALUES(3,1,'A11-3',80);
INSERT INTO product_variant VALUES(4,2,'A12-1',20);
INSERT INTO product_variant VALUES(5,2,'A12-2',30);
INSERT INTO product_variant VALUES(6,2,'A12-3',80);
INSERT INTO product_variant VALUES(7,2,'A12-4',90);
INSERT INTO product_variant VALUES(8,3,'B11-1',70);
INSERT INTO product_variant VALUES(9,3,'B11-2',70);

INSERT INTO sold_product VALUES(1,1,1,20,'2021-04-01');
INSERT INTO sold_product VALUES(2,1,1,15,'2021-04-01');
INSERT INTO sold_product VALUES(3,1,2,15,'2021-04-04');
INSERT INTO sold_product VALUES(4,1,3,10,'2021-04-05');
INSERT INTO sold_product VALUES(5,1,3,19,'2021-04-07');
INSERT INTO sold_product VALUES(6,2,4,11,'2021-04-07');
INSERT INTO sold_product VALUES(7,2,5,12,'2021-04-08');
INSERT INTO sold_product VALUES(8,2,7,15,'2021-04-10');
INSERT INTO sold_product VALUES(9,2,7,15,'2021-04-10');

First idea:

SELECT p.id, p.code,
    (
        SELECT SUM(v.initial_quantity)
        FROM product_variant AS v
        WHERE p.id = v.product_id
    ) AS initial_quantity,
    (
        SELECT SUM(s.quantity)
        FROM sold_product AS s
        WHERE p.id = s.product_id
    ) AS sold_quantity
FROM product AS p
ORDER BY sold_quantity;

Second idea:

SELECT p.id, p.code,
    (
        SELECT SUM(v.initial_quantity)
        FROM product_variant AS v
        WHERE p.id = v.product_id
    ) AS initial_quantity,
    SUM(s.quantity) AS sold_quantity
FROM sold_product AS s
INNER JOIN product AS p ON s.product_id = p.id
GROUP BY p.code, p.id,
    (
        SELECT SUM(v.initial_quantity)
        FROM product_variant AS v
        WHERE p.id = v.product_id
    )
ORDER BY sold_quantity;

EDIT: JOIN attempt, returns single result with sum of all sold quantities

SELECT p.id, p.code,
    (
        SELECT SUM(v.initial_quantity)
        FROM product_variant AS v
        WHERE p.id = v.product_id
    ) AS initial_quantity,
    SUM(s.quantity) AS sold_quantity
FROM product AS p
JOIN sold_product AS s ON p.id = s.product_id
ORDER BY sold_quantity;

Answer 1

Solved - missing index key on sold_product.product_id . I never thought missing index key could slow queries that much , up to 30 seconds. With that index key it takes 0.1s.

Thank you all who tried to help!