PostgreSQLの時間は、賢明なカウントデータ

Question

I have simple table 

    discount_code | updated_date 
    ---------------------------- 
    L1   | 2017-02-01 06:49:27 
    L1   | 2017-02-01 09:35:39 
    L1   | 2017-02-01 09:51:41 
    //etc 
I want result in PostgreSQL like below, 

    time_range  | count 
    ---------------------------- 
    00:00-01:00 | 0 
    01:00-02:00 | 0 
    //etc 
    06:00-07:00 | 1 
    09:00-10:00 | 2 

私は賢いrecord.My正確な概念がcount.Iは、クエリの下にしようとしているが、働いていない午前と賢明なグラフの時間をプロットすることである時間をカウントしたい、

select count(range) as ranges, 
    case 
    when to_char(updated_date,'HH:MI') >=00:00 and to_char(updated_date,'HH:MI')<=01:00 then '00:00-01:00' 
    when to_char(updated_date,'HH:MI') >=01:00 and to_char(updated_date,'HH:MI')<=02:00 then '01:00-02:00' 
    when to_char(updated_date,'HH:MI') >=02:00 and to_char(updated_date,'HH:MI')<=03:00 then '02:00-03:00' 
    when to_char(updated_date,'HH:MI') >=03:00 and to_char(updated_date,'HH:MI')<=04:00 then '03:00-04:00' 
    when to_char(updated_date,'HH:MI') >=04:00 and to_char(updated_date,'HH:MI')<=05:00 then '04:00-05:00' 
    when to_char(updated_date,'HH:MI') >=05:00 and to_char(updated_date,'HH:MI')<=06:00 then '05:00-06:00' 
    when to_char(updated_date,'HH:MI') >=06:00 and to_char(updated_date,'HH:MI')<=07:00 then '06:00-07:00' 
    when to_char(updated_date,'HH:MI') >=07:00 and to_char(updated_date,'HH:MI')<=08:00 then '07:00-08:00' 
    when to_char(updated_date,'HH:MI') >=08:00 and to_char(updated_date,'HH:MI')<=09:00 then '08:00-09:00' 
    when to_char(updated_date,'HH:MI') >=09:00 and to_char(updated_date,'HH:MI')<=10:00 then '09:00-10:00' 
    when to_char(updated_date,'HH:MI') >=10:00 and to_char(updated_date,'HH:MI')<=11:00 then '10:00-11:00' 
    when to_char(updated_date,'HH:MI') >=11:00 and to_char(updated_date,'HH:MI')<=12:00 then '11:00-12:00' 
    when to_char(updated_date,'HH:MI') >=12:00 and to_char(updated_date,'HH:MI')<=13:00 then '12:00-13:00' 
    //etc 
    else '' end AS range from 
    from my_table 
    where date(updated_date)=='2017-02-01' 

Answer 1

何についての範囲このようなもので、別の日付機能で時間範囲をフォーマットすることができます。

DEMO

SELECT date_trunc('hour', "updated_date") as hour, count(*) 
FROM Table1 
GROUP BY date_trunc('hour', "updated_date") 
ORDER BY 1 

OUTPUT

EDIT：より完全なバージョンを使用すると、範囲を計算する必要があります。

DEMO 2:

WITH parameter as (
    SELECT '2017-02-01'::date as d 
), hours (id, t) as (
    SELECT 1, '00:00'::time t UNION ALL 
    SELECT 2, '01:00'::time UNION ALL 
    SELECT 3, '02:00'::time UNION ALL 
    SELECT 4, '03:00'::time UNION ALL 
    SELECT 5, '04:00'::time UNION ALL 
    SELECT 6, '05:00'::time UNION ALL 
    SELECT 7, '06:00'::time UNION ALL 
    SELECT 8, '07:00'::time UNION ALL 
    SELECT 9, '08:00'::time UNION ALL 
    SELECT 10, '09:00'::time UNION ALL 
    SELECT 11, '10:00'::time UNION ALL 
    SELECT 12, '11:00'::time UNION ALL 
    SELECT 13, '12:00'::time UNION ALL 
    SELECT 14, '13:00'::time UNION ALL 
    SELECT 15, '14:00'::time UNION ALL 
    SELECT 16, '15:00'::time UNION ALL 
    SELECT 17, '16:00'::time UNION ALL 
    SELECT 18, '17:00'::time UNION ALL 
    SELECT 19, '18:00'::time UNION ALL 
    SELECT 20, '19:00'::time UNION ALL 
    SELECT 21, '20:00'::time UNION ALL 
    SELECT 22, '21:00'::time UNION ALL 
    SELECT 23, '22:00'::time UNION ALL 
    SELECT 24, '23:00'::time UNION ALL 
    SELECT 25, '24:00'::time 
), ranges as (
SELECT d + h1.t from_time, 
     d + h2.t to_time 
FROM parameter 
CROSS JOIN hours h1 
INNER JOIN hours h2 
     ON h1.id = h2.id - 1 
)  
SELECT from_time, to_time, count(t.updated_date) 
FROM ranges r 
LEFT JOIN Table1 t 
    ON t.updated_date >= r.from_time 
AND t.updated_date < r.to_time 
GROUP BY from_time, to_time 
ORDER BY from_time 

OUTPUT

Answer 2

試してみてください。

select lpad(hr::text, 2, '0')||':00-'||lpad((hr+1)::text, 2, '0')||':00' as time_range, 
     count(discount_code) 
from (
     select * 
     from generate_series(0,23) hr 
) x 
left join my_table t on x.hr = extract(hour from t.UPDATED_DATE) 
group by lpad(hr::text, 2, '0')||':00-'||lpad((hr+1)::text, 2, '0')||':00' 

Answer 3

使用あなたはデータがない結果を得るために機能：

select to_char(h, 'HH24:MI-') || to_char(h + interval '1 hour', 'HH24:MI') time_range, 
      count(discount_code) 
from  generate_series(timestamp '2017-02-01', 
          timestamp '2017-02-02' - interval '1 hour', 
          interval '1 hour') h 
left join simple_table on updated_date >= h and updated_date < (h + interval '1 hour') 
group by h 
order by h; 

http://rextester.com/EBBCL23865