Как Объединить Same PostgreSQL Data

Question

У меня есть PostGreSQL заявление, которое:

(select cast(start_time as date) as time , SUM(count) as count 
from tbl_product 
where (cast(start_time as date) >= '2016-08-30 23:00:00' and cast(start_time as date) <= '2016-09-01 20:00:00') 
and (extract(hour from start_time) >= 23 and extract(hour from start_time) <= 24)  
group by time order by time limit 5) 

UNION (select cast(start_time as date) as time , SUM(count) as count 
from tbl_product 
where (cast(start_time as date) >= '2016-08-31 23:00:00' and cast(start_time as date) <= '2016-09-01 20:00:00') 
and (extract(hour from start_time) >= 0 and extract(hour from start_time) < 20)  
group by time order by time limit 5) 

Но он возвращает те же данные для той же даты, из-за UNION заявления

time   count 
date   numeric 
"2016-08-31" 543595 
"2016-08-31" 3666277 
"2016-09-01" 3365093 

Как я могу добавьте эти значения данных, например:

time   count 
date   numeric 
"2016-08-31" 4209872 
"2016-09-01" 3365093 

Спасибо за помощь.

Answer 1

Вам необходимо переместить GROUP BY из отдельных запросов. Нечто подобное:

SELECT time, SUM(count) as count FROM (
    (select cast(start_time as date) as time , count 
    from tbl_product 
    where (cast(start_time as date) >= '2016-08-30 23:00:00' and cast(start_time as date) <= '2016-09-01 20:00:00') 
    and (extract(hour from start_time) >= 23)) 
     UNION ALL 
    (select cast(start_time as date) as time , count 
    from tbl_product 
    where (cast(start_time as date) >= '2016-08-31 23:00:00' and cast(start_time as date) <= '2016-09-01 20:00:00') 
    and (extract(hour from start_time) >= 0 and extract(hour from start_time) < 20)) 
    ) AS t 
GROUP BY time ORDER by time; 

Я также изменил UNION к UNION ALL, потому что, кажется, больше смысла в этом случае. Наконец, тест extract(hour from start_time) <= 24 всегда верен, поэтому он избыточен.

Answer 2

попробовать этот запрос:

select 
exe.time_, 
sum(exe.count_) 
from 
(
    select cast(start_time as date) as time_ , SUM(count) as count_ 
    from tbl_product 
    where (cast(start_time as date) >= '2016-08-30 23:00:00' and cast(start_time as date) <= '2016-09-01 20:00:00') 
    and (extract(hour from start_time) >= 23 and extract(hour from start_time) <= 24)  
    group by time order by time limit 5 
    UNION 
    select cast(start_time as date) as time_, SUM(count) as count_ 
    from tbl_product 
    where (cast(start_time as date) >= '2016-08-31 23:00:00' and cast(start_time as date) <= '2016-09-01 20:00:00') 
    and (extract(hour from start_time) >= 0 and extract(hour from start_time) < 20)  
    group by time order by time limit 5 
) exe 
group by exe.time_