Postgres查询将15分钟间隔转换为每小时间隔

Question

我想将postgres数据库中的15分钟间隔表转换为每小时间隔，并将其他列中的所有值相加。我该怎么做呢？查询会是什么？

示例：

timestamp                    count
"2015-01-05 12:00:00"          35
"2015-01-05 12:15:00"       45
"2015-01-05 12:30:00"       23
"2015-01-05 12:45:00"       23
"2015-01-05 01:00:00"       45
"2015-01-05 01:15:00"       12
"2015-01-05 01:30:00"       11
"2015-01-05 01:45:00"        56

我希望输出表是

timestamp                  count
2015-01-05 12:00:00         126
2015-01-05 01:00:00         124

Answer 1

简单，在PostgreSQL中：

SELECT date_trunc('hour', timestamp_col) as ts_hour, sum(count_col) 
FROM counts_table
GROUP BY ts_hour
ORDER BY ts_hour;

Answer 2

FuzzChef提供了一个很好的答案，但您可能需要将别名从别名更改为实际的date_trunc，如下所示：

SELECT date_trunc('hour', timestamp_col) as ts_hour, sum(count_col) FROM counts_table 
GROUP BY date_trunc('hour', timestamp_col) 
ORDER BY date_trunc('hour', timestamp_col) 
;

此外，如果您只是希望HOUR出现，请使用extract，如下所示：

SELECT extract('hour' from timestamp_col) as ts_hour, sum(count_col) FROM counts_table 
GROUP BY extract('hour' from timestamp_col) 
ORDER BY extract('hour' from timestamp_col) 
;