我目前使用這樣的:如何獲得時間戳的平均值? PostgreSQL的
select avg(tank_level)
from (
select row_number() over (order by id) as rn, tank_level
from data_tanksensor
where sensors_on_site_id = 91
) s
group by (rn + ((Select count(*)/10 From data_tanksensor where sensors_on_site_id = 91)-1))/ (Select count(*)/10 From data_tanksensor where sensors_on_site_id = 91)
;
要想從表10點的平均值。此表還包含時間戳,我希望獲得10個平均tank_level的平均時間戳。這被用來創建一個歷史圖。如果任何人都可以幫助我修改此查詢,以獲得平均時間戳,將不勝感激。提前致謝。
的表看起來像這樣
. id sensors_on_site_id tank_level timestamps [PK] bigint integer double precision time without time zone ........... .................. ................ ...................... 12345 91 7.5 2017-03-24 11:16:31.143362 12346 91 7.6 2017-03-24 11:21:31.148639 12347 91 5.4 2017-03-24 11:26:31.155739 12348 91 3.6 2017-03-24 11:31:31.156478 12349 91 8.5 2017-03-24 11:36:31.157303 12350 91 4.2 2017-03-24 11:41:31.172008
再舉例來說,如果我只希望這是我原來的查詢均線將
select avg(tank_level) from ( select row_number() over (order by id) as rn, tank_level from data_tanksensor where sensors_on_site_id = 91 ) s group by (rn + ((Select count(*)/2 From data_tanksensor where sensors_on_site_id = 91)-1))/ (Select count(*)/2 From data_tanksensor where sensors_on_site_id = 91) ;
粗的 查詢丟失,將平均時間戳的部分這正是我想弄明白的。但我試圖得到的預期結果是
avg timestamp double precision timestamp without time zone ................ ........................... 6.833333 2017-03-24 11:21:31... 5.433333 2017-03-24 11:36:31...
再次,這只是樣本數據,一次數百行的平均行數。謝謝
請編輯您的問題,並提供樣本數據和預期的結果。 F.ex. –
F.ex. 'to_timestamp(avg(摘錄(從timestamp_col開始))''? – pozs