How to calculate the initial Stock with MySql - mysql

Question

I'm trying to find a way to calculate the initial stock by the number of weeks.
I'm have just managed to calculate the 'in' and 'out' of stock between the weeks 10 and 20 with this request.
Can someone give me the full request to calculate the final stock and the initial stock.
SELECT
`week` ,
SUM(case
when `week` between 10 AND 20 and `etat` =1
then 1
else 0
end) AS inn
,
SUM(case
when `week` between 10 AND 20 and `etat` =2
then 1
else 0
end) AS out
FROM fait_stock f
where 1=1
group by `week`
having `week` between 10 AND 20
EDIT
I want to calculate the stock of the previous weeks (initial stock that means weeks<10) for example week 10 I have 5. week 11 It should be 5+(stock of week 11). Week 12 it should be 5+(stock of week 11)+(stock of week 12) the same for others weeks.

Answer 1

First of all - you can write your query much shorter:
SELECT
`week` ,
SUM(IF(`etat`=1, 1, 0)) AS inn,
SUM(IF(`etat`=2, 1, 0)) AS `out`
FROM fait_stock
WHERE `week` BETWEEN 10 AND 20
GROUP BY `week`
If you now join it with itself (with a small modification, if you want the sums of weeks < 10), you can calculate the sums for all weeks that are smaller or equal than the given week:
SELECT f1.`week`, SUM(f2.inn) AS inn, SUM(f2.`out`) AS `out`
FROM (
SELECT
`week` ,
SUM(IF(`etat`=1, 1, 0)) AS inn,
SUM(IF(`etat`=2, 1, 0)) AS `out`
FROM fait_stock
WHERE `week` BETWEEN 10 AND 20
GROUP BY `week`
) AS f1
JOIN (
SELECT
`week` ,
SUM(IF(`etat`=1, 1, 0)) AS inn,
SUM(IF(`etat`=2, 1, 0)) AS `out`
FROM fait_stock
WHERE `week` BETWEEN 1 AND 20
GROUP BY `week`
) AS f2 ON f2.`week` <= f1.`week`
GROUP BY f1.`week`