SQLite: Group data within certain time interval - sqlite

Question

I have a single table which stores data of orders:
Orders Table:
id | order_time | quantity | ...
1 | 1592821854318 | 2
2 | 1592901538199 | 4
3 | 1592966454547 | 1
4 | 1593081282406 | 9
5 | 1593141826330 | 6
order_time table is UNIX timestamp.
Using below query I am able to get available data grouped by days (86400000 = 24 hours):
SELECT order_time+ (86400000 - (order_time % 86400000)) as gap, SUM(quantity) as
totalOrdersBetweenInterval
FROM USAGE_DETAILS ud
WHERE order_time >= 1590969600 AND order_time <= 1593388799000
GROUP BY gap
ORDER BY gap ASC
Suppose for this month of June, I receive order on 1, 4, 6, 7 date then by using above query I am able to retrieve data as follow :
gap | totalOrdersBetweenInterval
1 | 5
4 | 6
6 | 4
7 | 10
I would receive UNIX timestamp in gap column but for the sake of example I have used readable dates.
Above query will only retrieve data for the days which would have received order but I want to split data in range like below which also include days with no orders :
gap | totalOrdersBetweenInterval
1 | 5
2 | 0
3 | 0
4 | 6
5 | 0
6 | 4
7 | 10
8 | 0
9 | 0
. | .
. | .
How do I go about that?

Answer 1

You need a query that returns 30 rows:1,2,...,30 for the days of June.
You could do it with a recursive CTE:
with days as (
select 1 day
union all
select day + 1
from days
where day < 30
)
but I'm not sure if Android uses a version of SQLite that supports CTEs.
If it does support them, all you need to do is join the CTE with a LEFT join to your query:
with
days as (
select 1 day
union all
select day + 1
from days
where day < 30
),
yourquery as (
<your query here>
)
select d.day, coalesce(t.totalOrdersBetweenInterval, 0) totalOrdersBetweenInterval
from days d left join yourquery t
on t.gap = d.day
If Android does not support CTEs you will have to build the query that returns the days with UNION ALL:
select d.day, coalesce(t.totalOrdersBetweenInterval, 0) totalOrdersBetweenInterval
from (
select 1 day union all select 2 union all
select 3 union all select 4 union all
......................................
select 29 union all select 30
) d left join (
<your query here>
) t
on t.gap = d.day

Answer 2

Thanks to #forpas for helping me out.
Just posting in case someone is searching for slicing data by unix time intervals.
with
days as (
select 1590969600000 day --Starting of June 1 2020
union all
select day + 86400000 --equivalent to 1 day
from days
where day < 1593388799000 --Less than 28th of June
),
subquery as (
SELECT order_time+ (86400000 - (order_time % 86400000)) as gap, SUM(quantity) as
totalOrdersBetweenInterval
FROM USAGE_DETAILS ud
WHERE order_time >= 1590969600000 AND order_time <= 1593388799000
GROUP BY gap
)
select d.day, coalesce(t.totalOrdersBetweenInterval, 0) totalOrdersBetweenInterval
from days d left join subquery t
on t.gap = d.day
order by d.day