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[英]Access SQL - I need a query to count fields based on several criteria
[英]SQL query to find duration based on several criteria
我有一個名為status
的表,其中包含以下數據:
time var value
12:00:01 a 10
12:00:01 b 10
12:00:01 c 12
12:00:05 a 9
12:00:05 b 10
12:00:05 c 10
12:00:10 a 13
12:00:10 b 1
12:00:10 c 4
14:00:01 a 12
14:00:01 b 11
14:00:01 c 9
14:00:41 a 9
14:00:41 b 9
14:00:41 c 3
現在我想找到A > 10
和B > 10
我想要答案的持續時間:44 秒(持續時間從 12:00:01 到 12:00:05 = 4 秒,持續時間從 14:00:01 到14:00:41 = 40 秒,總共 44 秒)我試過:
SELECT sum(time) as duration FROM status WHERE A>10 AND B>10;
這是一個間隙和孤島問題,可以使用累積和來解決。 lag()
用於確定島嶼的開始位置。 累積總和定義組。
眾所周知,SQL 日期/時間函數依賴於數據庫。 所以下面給出了正確的想法,但它可能無法直接在您的數據庫中工作。 因此,條件發生的時間由以下查詢返回:
select min(time), max(time)
from (select t.*,
sum(case when a < 10 or b < 10 then 1 else 0 end) over (order by time) as grp
from status t
) t
where a > 10 and b > 10;
sum()
然后是對此的聚合。 例如:
select sum(maxtime - mintime)
from (select max(time) as maxtime, min(time) as mintime
from (select t.*,
sum(case when a < 10 or b < 10 then 1 else 0 end) over (order by time) as grp
from status t
) t
where a > 10 and b > 10
) t
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