[英]postgres weekday frequency by hours
我想生成一個類似下面的報告(來自Google Analytics App for Android的屏幕截圖)
我發生的事件每天發生10-15次,我希望每個工作日都能看到從一開始就以小時為單位的頻率。
我只需要使用名為“created_at”的DateTime(時間戳)字段(是一個Rails項目)
我怎么能在PostgreSQL中做到這一點?
謝謝
這很容易。 您只需按一天中的小時和當天的日期分組,然后計算,有多少元素。 結果的前兩列(日期和日期的小時)是圖表中相應單元格的2D坐標。 第三列(計數)為您提供該單元格的顏色。
一個例子:
SELECT
extract('hour' FROM starttime) as hour,
date_trunc('day', starttime) as day,
count(*) as nbmr
FROM actions
GROUP BY hour, day;
( 現場小提琴 )
在此示例中,“hour”和“day”列對應於圖表中單元格的y軸和x軸。 然后,列“nmbr”會告訴您該單元格的顏色。
您可以輕松修改此查詢,例如按工作日顯示百分比和組(0表示星期日):
SELECT
extract('hour' FROM starttime) as hour,
extract('dow' FROM starttime) as day,
count(*) * 100.0 / (select count(*) from actions) as nbmr
FROM actions
GROUP BY hour, day;
( 現場小提琴 )
已經提供的答案都是正確的,但只是為了變化,這里使用' tablefunc '擴展來交叉列表結果,使其看起來完全符合您的樣本。
在使用它之前,您必須創建tablefunc擴展(在postgresql的contrib包中可用):
CREATE EXTENSION IF NOT EXISTS tablefunc;
這是查詢,假設輸入數據在表t的created_at列中:
SELECT * FROM CROSSTAB($$SELECT h.hour AS hour_of_day,
dow.day AS day,
COUNT(t.created_at)::INT
FROM (values('Mon'),('Tue'),('Wed'),('Thu'),('Fri'),('Sat'),('Sun')) AS dow(day)
CROSS JOIN generate_series(0,23) as h(hour)
LEFT JOIN t ON to_char(t.created_at, 'Dy')=dow.day AND extract(hour from t.created_at)=h.hour
GROUP BY dow.day,h.hour
ORDER BY h.hour,dow.day$$) AS d(Hour int, "Mon" int,"Tue" int,"Wed" int,"Thu" int,"Fri" int,"Sat" int,"Sun" int);
要點:
結果如下:
hour | Mon | Tue | Wed | Thu | Fri | Sat | Sun
------+-----+-----+-----+-----+-----+-----+-----
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0
1 | 0 | 0 | 0 | 0 | 0 | 0 | 0
2 | 0 | 0 | 0 | 0 | 0 | 0 | 0
3 | 0 | 0 | 0 | 0 | 0 | 0 | 0
4 | 0 | 0 | 0 | 0 | 0 | 0 | 0
5 | 0 | 0 | 0 | 0 | 0 | 0 | 0
6 | 0 | 0 | 0 | 0 | 0 | 0 | 0
7 | 0 | 0 | 0 | 0 | 0 | 0 | 0
8 | 0 | 0 | 0 | 0 | 0 | 0 | 0
9 | 0 | 0 | 0 | 0 | 0 | 0 | 0
10 | 0 | 0 | 0 | 0 | 0 | 0 | 1
11 | 0 | 0 | 0 | 0 | 0 | 0 | 0
12 | 0 | 0 | 0 | 0 | 0 | 0 | 0
13 | 0 | 0 | 0 | 1 | 0 | 0 | 0
14 | 0 | 0 | 0 | 0 | 0 | 0 | 0
15 | 0 | 0 | 0 | 0 | 0 | 0 | 0
16 | 0 | 0 | 0 | 0 | 0 | 0 | 0
17 | 0 | 0 | 1 | 0 | 0 | 0 | 0
18 | 0 | 0 | 0 | 0 | 0 | 0 | 0
19 | 0 | 0 | 0 | 0 | 0 | 0 | 0
20 | 0 | 0 | 0 | 0 | 0 | 0 | 0
21 | 0 | 0 | 0 | 0 | 0 | 0 | 0
22 | 0 | 0 | 0 | 0 | 0 | 0 | 0
23 | 0 | 0 | 0 | 0 | 1 | 0 | 0
(24 rows)
這是從這個示例數據生成的:
created_at
----------------------------
2014-06-12 23:06:03.746884
2014-01-15 10:00:00
2014-05-25 13:00:00
2014-03-01 17:00:00
(4 rows)
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