我需要按照一天的时间进行分组,并划分为2个小时:
我使用了EXTRACT PostgreSQL函数。但是无法找到一种以2小时的时间分组的方法
SELECT EXTRACT(dow from completed_at) AS "day",
EXTRACT(hour from completed_at) AS "hour", count(*)
FROM orders
WHERE completed_at is not null
GROUP BY 1, 2
ORDER BY 1;
预期输出:
day hour count
-------- ------ ------
Sun 12am 10
Sun 2am 8
Sun 4am 0
Sun 6am 24
Sun 8am 25
Sun 10am 100
Sun 12pm 67
Sun 2pm 10
Sun 4pm 10
Sun 6pm 10
Sun 8pm 10
Sun 10pm 10
那样,我在所有工作日都需要
答案 0 :(得分:2)
尝试:
SELECT EXTRACT(dow from completed_at) AS "day",
EXTRACT(hour from completed_at) AS "hour", count(*)
FROM orders
join generate_series(0,22,2) g on g >= extract(hour from completed_at) and g< extract(hour from completed_at) + 2
WHERE completed_at is not null
GROUP BY "day","hour"
ORDER BY 1;
就像在我的示例模式中一样:
db=# create table so (t timestamptz);
CREATE TABLE
Time: 171.144 ms
db=# insert into so select generate_series(now(),current_date + 2,' 1hour'::interval);
INSERT 0 40
Time: 71.150 ms
db=# select count(*), g
from so
join generate_series(0,22,2) g on g >= extract(hour from t) and g< extract(hour from t) + 2
group by g
order by 2,1
;
count | g
-------+----
1 | 0
2 | 2
2 | 4
2 | 6
3 | 8
4 | 10
4 | 12
4 | 14
4 | 16
4 | 18
4 | 20
4 | 22
2 | 24
(13 rows)
Time: 11.958 ms
答案 1 :(得分:0)
我使用了纪元(秒),然后转换为2小时
SELECT EXTRACT(dow from completed_at) AS "Day",
EXTRACT(hour from (to_timestamp(floor((extract('epoch' from completed_at) / (60 * 60 * 2) )) * (60 * 60 * 2))
AT TIME ZONE 'UTC')),
COUNT(*)
FROM orders
WHERE completed_at is not null
GROUP BY 1, 2
ORDER BY 1;