mysql Cumulative sum for each unique ID in each sale: - mysql

Question

I have trouble adding and accumulating my amounts per id,
I use this solution but it doesn't work and it adds up all the ids,
id product_id quantity acumulado
168 190 1 1
169 190 3 4
170 195 1 5
171 190 25.60 30.60
172 190 1 31.60
I use this:
SET #csum := 0;
UPDATE sma_sale_items
SET acumulado = (#csum := #csum + quantity)
ORDER BY id, product_id;
any solution? ineed this
id product_id quantity acumulado
168 190 1 1
169 190 3 4
170 195 1 1
171 190 25.60 29.60
172 190 1 30.60
For version 5.7 ?

Answer 1

You can use a SELECT statement containing window analytic function instead of an UPDATE statement :
SELECT id, product_id, quantity, SUM(quantity) OVER (ORDER BY id) AS acumulado
FROM sma_sale_items
acumulado column shouldn't need to be stored within a table being a computable column.
Demo1
If you still prefer UPDATE, then use :
UPDATE sma_sale_items s1
JOIN (
SELECT id, product_id, SUM(quantity) OVER (ORDER BY id) AS acumulado
FROM sma_sale_items
ORDER BY id
) s2 ON s1.ID=s2.ID
SET s1.acumulado = s2.acumulado;
Demo2
UPDATE : Depending on the last edit consider using
SUM(quantity) OVER (PARTITION BY product_id ORDER BY id) AS acumulado
instead of SUM(quantity) OVER (ORDER BY id) AS acumulado
by adding PARTITION BY product_id in order to distinguish the sums grouped by product_id
Demo3