Postgres grouping by range - sql

Question

I have data looking like this
What I am trying to achieve is data for historgram that would count values into specific ranges. For category A value range 1-100 and for category B value range 0-125 where value for category C = 5. The problem I have that is data in multiplerows and I need to filter first on C and then count values into ranges to display histogram.
To get counts lets say per 10 seconds looking like this
Code to generate data:
CREATE TEMP TABLE sample (
ts timestamp
,category varchar(2)
, val int)
insert into sample values
(to_timestamp('01.01.2018 08:00:01', 'dd-mm-yyyy hh24:mi:ss'), 'A', 12),
(to_timestamp('01.01.2018 08:00:02', 'dd-mm-yyyy hh24:mi:ss'), 'A', 44),
(to_timestamp('01.01.2018 08:00:03', 'dd-mm-yyyy hh24:mi:ss'), 'C', 1),
(to_timestamp('01.01.2018 08:00:04', 'dd-mm-yyyy hh24:mi:ss'), 'B', 24),
(to_timestamp('01.01.2018 08:00:05', 'dd-mm-yyyy hh24:mi:ss'), 'B', 111),
(to_timestamp('01.01.2018 08:00:06', 'dd-mm-yyyy hh24:mi:ss'), 'C', 5),
(to_timestamp('01.01.2018 08:00:07', 'dd-mm-yyyy hh24:mi:ss'), 'A', 145),
(to_timestamp('01.01.2018 08:00:01', 'dd-mm-yyyy hh24:mi:ss'), 'B', 16),
(to_timestamp('01.01.2018 08:00:01', 'dd-mm-yyyy hh24:mi:ss'), 'C', 47),
(to_timestamp('01.01.2018 08:00:02', 'dd-mm-yyyy hh24:mi:ss'), 'C', 5),
(to_timestamp('01.01.2018 08:00:02', 'dd-mm-yyyy hh24:mi:ss'), 'B', 34),
(to_timestamp('01.01.2018 08:00:03', 'dd-mm-yyyy hh24:mi:ss'), 'B', 111),
(to_timestamp('01.01.2018 08:00:03', 'dd-mm-yyyy hh24:mi:ss'), 'C', 5),
(to_timestamp('01.01.2018 08:00:01', 'dd-mm-yyyy hh24:mi:ss'), 'A', 19),
(to_timestamp('01.01.2018 08:00:01', 'dd-mm-yyyy hh24:mi:ss'), 'B', 46),
(to_timestamp('01.01.2018 08:00:01', 'dd-mm-yyyy hh24:mi:ss'), 'C', 57)
I thought if I pivot data like so
s
elect
ts,
category,
case when category = 'A' then val end as "A",
case when category = 'B' then val end as "B",
case when category = 'C' then val end as "C"
from sample
order by ts
then have problem with pivot nulls

Answer 1

Here it is:
with periods(pts) as
(
select *
from generate_series
(
timestamp '2018-01-01 08:00:00',
timestamp '2018-01-01 08:01:00',
interval '10 seconds'
) ts
)
select pts period_start,
pts + interval '10 seconds' period_end,
lat.cat_a,
lat.cat_b,
lat.cat_c
from periods
cross join lateral
(
select count(1) filter (where category = 'A' and val between 0 and 100) as cat_a,
count(1) filter (where category = 'B' and val between 0 and 125) as cat_b,
count(1) filter (where category = 'C' and val = 5) as cat_c
from sample
where ts >= pts and ts < pts + interval '10 seconds'
) lat;
period_start
period_end
cat_a
cat_b
cat_c
2018-01-01 08:00:00
2018-01-01 08:00:10
2
2
1
2018-01-01 08:00:10
2018-01-01 08:00:20
0
0
0
2018-01-01 08:00:20
2018-01-01 08:00:30
0
0
0
2018-01-01 08:00:30
2018-01-01 08:00:40
0
0
0
2018-01-01 08:00:40
2018-01-01 08:00:50
0
0
0
2018-01-01 08:00:50
2018-01-01 08:01:00
0
0
0
2018-01-01 08:01:00
2018-01-01 08:01:10
0
0
0
One-row version is simple:
select min(ts) period_start,
max(ts) period_end,
count(1) filter (where category = 'A' and val between 0 and 100) as cat_a,
count(1) filter (where category = 'B' and val between 0 and 125) as cat_b,
count(1) filter (where category = 'C' and val = 5) as cat_c
from sample;
Added after the clarification comments
select * from (<the first version of the query here>) t where cat_c > 0;