Sum all values in a column and group by 2 minutes - sql

Question

I want to sum all values in a column "value" and group by a interval of 2 minutes
I have values like this:
value TIME
0.3 2019-05-22 01:11:45---> first value 0,3
0.3 2019-05-22 01:12:16-----|
0.3 2019-05-22 01:13:26-----|second value 0,6
0.2 2019-05-22 01:13:56---|
0.4 2019-05-22 01:14:06---|
0.6 2019-05-22 01:15:43 --|third value 1,2
But what I really want is like this:
value TIME
0.3 2019-05-22 01:11:45
0.6 2019-05-22 01:13:45
1.2 2019-05-22 01:15:45
My code in postgresql:
SELECT medi_sensor.value, time
FROM medi_sensor
JOIN sensor ON medi_sensor.sensor_name = sensor.name
JOIN mote ON num_mot=mot_id
JOIN room ON room_id=id_div
WHERE medi_sensor.sensor_name LIKE 'current%' AND room.name='DIV' AND time>'2019-05-22' AND time<'2019-05-24'
ORDER BY time ASC
The problem is how to group by minute to minute in my time column

Answer 1

In Postgres, you can use generate_series() to generate the values:
select gs.t, sum(value)
from (select ms.value, time, min(time) over () as min_time, max(time) over () as max_time
from medi_sensor ms join
sensor s
on ms.sensor_name = s.name join
mote
on num_mot = mot_id join
room r
on room_id = id_div
where ms.sensor_name LIKE 'current%' and
r.name = 'DIV' and
time > '2019-05-22' and
time < '2019-05-24'
) x right join lateral
generate_series(min_time, max_time, interval '2 minute') gs(t)
on time >= gs.t and time < ts.t + interval '2 minute'
order by gs.t;
I would recommend that you use table aliases for all column references in your query.
EDIT:
with x as (
select ms.value, time
from medi_sensor ms join
sensor s
on ms.sensor_name = s.name join
mote
on num_mot = mot_id join
room r
on room_id = id_div
where ms.sensor_name LIKE 'current%' and
r.name = 'DIV' and
time > '2019-05-22' and
time < '2019-05-24'
) x
select gs.ts, sum(x.value)
from (select generate_series(min_time, max_time, interval '2 minute') as ts
from (select min(time) as min_time, max(time) as max_time
from x
)
) gs left join
x
on x.time >= gs.t and x.time < ts.t + interval '2 minute'
group by gs.ts
order by gs.ts;