想要使用sql计算begintime和endtime的在线人数

Question

我想在presto上使用带有begintime和endtime的sql在线人员计数

我的数据类似：

userid  begintime   endtime
023150000030040 2020-03-05 12:50:46 2020-03-05 12:50:49
023150004186637 2020-03-05 10:31:19 2020-03-05 10:31:24
023150000788581 2020-03-05 00:59:01 2020-03-05 01:02:00
023150004411606 2020-03-05 19:55:42 2020-03-05 20:02:51
023150004066308 2020-03-05 18:48:03 2020-03-05 18:58:03
023150002033547 2020-03-05 12:39:24 2020-03-05 12:42:21
023150000030040 2020-03-05 13:26:02 2020-03-05 13:26:04
023150003690798 2020-03-05 02:04:50 2020-03-05 02:14:50
023150000030040 2020-03-05 13:57:10 2020-03-05 13:57:12
023150004460558 2020-03-05 16:44:48 2020-03-05 16:47:58

我想每小时统计一次在线人数。现在我有一个愚蠢的计数方法。我的sql类：

select '01' as hour,COUNT(distinct T.userid)
from datamart_ott_b2b_jsydcp.f_tplay t where t.topicdate  ='2020-03-05'   
and t.begintime < date_parse('2020-03-05 01', '%Y-%m-%d %h')
and t.endtime > date_parse('2020-03-05 00', '%Y-%m-%d %h')
union all 
select  '02' as hour,COUNT(distinct T.userid)
from datamart_ott_b2b_jsydcp.f_tplay t where t.topicdate  ='2020-03-05'   
and t.begintime < date_parse('2020-03-05 02', '%Y-%m-%d %h')
and t.endtime > date_parse('2020-03-05 01', '%Y-%m-%d %h')
.......

有更简单的方法吗？THX

Answer 1

在Prestodb中，您可以生成一个具有整数值的数组，然后对它们进行unest以获得小时数。然后使用join和group by进行您想要的计算：

select hh.hh as hour, cont(distinct t.userid)
from (select sequence(0, 23) hhs
) h cross join
unnest(h.hhs)  as hh(hh) left join
datamart_ott_b2b_jsydcp.f_tplay t
on hour(begintime) <= hh.hh and
hour(enddtime) >= hh.hh
where t.topicdate  = '2020-03-05'  
group by hh.hh
order by hh.hh;

Answer 2

使用日历表方法，我们可以将包含所有24小时的表左联接到当前表，条件是小时和日期都匹配。然后，我们可以按小时进行聚合，并对不同的用户进行计数，以生成您想要的输出。

WITH hours AS (
SELECT 0 AS hour UNION ALL
SELECT 1 UNION ALL
SELECT 2 UNION ALL
...
SELECT 23
)
SELECT
h.hour,
COUNT(DISTINCT t.userid) AS user_cnt
FROM hours h
LEFT JOIN datamart_ott_b2b_jsydcp.f_tplay t
ON h.hour = DATE_TRUNC('hour', t.topicdate) AND
t.topicdate = '2020-03-05'
GROUP BY
h.hour
ORDER BY
h.hour;