I have a bunch of records in the table below.
product_id produced_date expired_date
123 2010-02-01 2012-05-31
234 2013-03-01 2014-08-04
345 2012-05-01 2018-02-25
... ... ...
I want the output to display how many unexpired products currently we have at the monthly level. (Say, if a product expires on August 04, we still count it in August stock)
Month n_products
2010-02-01 10
2010-03-01 12
...
2022-07-01 25
2022-08-01 15
How should I do this in Presto or Hive? Thank you!
CodePudding user response:
You can use below SQL.
Here we are using case when
to check if a product is expired or not(produced_date >= expired_date
), if its expired, we are summing it to get count of product that has been expired. And then group that data over expiry month.
select
TRUNC(expired_date, 'MM') expired_month,
SUM( case when produced_date >= expired_date then 1 else 0 end) n_products
from mytable
group by 1
CodePudding user response:
We can use unnest and sequence functions to create a derived table; Joining our table with this derived table, should give us the desired result.
Select m.month,count(product_id) as n_products
(Select
(select x
from unnest(sequence(Min(month(produced_date)), Max(month(expired_date)), Interval '1' month)) t(x)
) as month
from table) m
left join table t on m.month >= t.produced_date and m.month <= t.expired_date
group by 1
order by 1