总和计算在几天和小时
我正在尝试使用Knex在多个小时内按小时对logging进行分组。 所以,例如,9AM将是:
{ hour: 9AM, // for days 12/11, 12/12, 12/13 count: 10 // 10 Ids total over those days for hour 9AM }
鉴于此快照中的logging,如何在多天内将它们汇总到小桶中?
如果输出查询结果,则可以在12/12
和12/13
19:00
看到两个单独的结果。 这两天的计数需要总结为一个hour 19:00
分组:
ROWS [ anonymous { session_ids: [ 3200 ], hour: 2016-12-12T14:00:00.000Z, count: '1' }, anonymous { session_ids: [ 3201 ], hour: 2016-12-12T15:00:00.000Z, count: '1' }, anonymous { session_ids: [ 3203, 3202 ], hour: 2016-12-12T19:00:00.000Z, count: '2' }, anonymous { session_ids: [ 3204, 3205 ], hour: 2016-12-13T19:00:00.000Z, // This count should be aggregated into the `19:00` grouping above count: '2' } ]
我目前的查询:
var qry = db.knex .select(db.knex.raw("array_agg(t2.id) as session_ids, date_trunc('hour', t2.start_timestamp) as hour")) .count('*') .from('sessions as t2') .groupByRaw("date_trunc('hour', t2.start_timestamp)") .orderBy(db.knex.raw("date_trunc('hour', t2.start_timestamp)"));
使用EXTRACT
,而不是date_trunc
:
var qry = db.knex .select(db.knex.raw("array_agg(t2.id) as session_ids, extract('hour' from t2.start_timestamp) as hour")) .count('*') .from('sessions as t2') .groupByRaw("extract('hour' from t2.start_timestamp)") .orderBy(db.knex.raw("extract('hour' from t2.start_timestamp)"));
date_trunc
将时间戳截断为指定的精度(这意味着GROUP BY
将不起作用,因为具有相同“小时”字段的两个时间戳的date可能仍然不同):
SELECT date_trunc('hour', NOW()); ┌────────────────────────┐ │ date_trunc │ ├────────────────────────┤ │ 2016-12-18 19:00:00+01 │ └────────────────────────┘ (1 row)
而EXTRACT
提取您要求的特定字段:
SELECT extract('hour' from NOW()); ┌───────────┐ │ date_part │ ├───────────┤ │ 19 │ └───────────┘ (1 row)