Counts for time range per day - sql

Question

I have a table something like this
create table widgets
(
id primary key,
created_at timestamp,
-- other fields
)
Now I want a query that shows the count of widgets with created_at between multiple time ranges for each day. For example, the count of widgets with created_at between 00:00:00 and 11:59:59 and the count between 12:00:00 and 23:59:59. The output would look something like this:
date | morning widgets (before noon) | evening widgets (after noon) |
---------------|-------------------------------|------------------------------|
2022-05-01 | ## | ## |
2022-05-02 | ## | ## |
2022-05-03 | ## | ## |
2022-05-04 | ## | ## |
... etc.
So far, I figured out I can get counts per day:
select created_at::date as created_at_date, count(*) as total
from widgets
where created_at::date >= '2022-05-01' -- where clause for illustration purposes only and not critical to the central question here
group by created_at::date
I'm learning about windowing functions, specifically partition by. I think this will help me get what I want, but not sure. How do I do this?
I'd prefer a "standard SQL" solution. If necessary, I'm on postgres and can use anything specific to its flavor of SQL.

Answer 1

If I understand correctly, we can try to use the condition window function to make it.
morning widgets (before noon) : between 00:00:00 and 11:59:59
evening widgets (after noon) : between 12:00:00 and 23:59:59
put the condition in aggregate function by CASE WHEN expression.
SELECT created_at::date,
COUNT(CASE WHEN created_at >= created_at::date AND created_at <= created_at::date + INTERVAL '12 HOUR' THEN 1 END) ,
COUNT(CASE WHEN created_at >= created_at::date + INTERVAL '12 HOUR' AND created_at <= created_at::date+ INTERVAL '1 DAY' THEN 1 END)
FROM widgets w
GROUP BY created_at::date
ORDER BY created_at::date
sqliddle