我在SQL中有一组数据,如下所示:
╔═══════════╦═══════╗
║ TimeStamp ║ State ║
╠═══════════╬═══════╣
║ 7:10 AM ║ A ║
║ 7:11 AM ║ A ║
║ 7:12 AM ║ A ║
║ 7:13 AM ║ B ║
║ 7:14 AM ║ B ║
║ 7:15 AM ║ A ║
║ 7:16 AM ║ A ║
║ 7:17 AM ║ C ║
║ 7:18 AM ║ C ║
╚═══════════╩═══════╝
我正在尝试计算每个状态的持续时间。但是,我想分离每个状态序列,并分别计算它们之间的差异,并分离重复的状态。因此,我希望以上数据返回类似以下内容的内容:
╔═══════╦════════════════════╗
║ State ║ Duration (minutes) ║
╠═══════╬════════════════════╣
║ A ║ 2 ║
║ B ║ 1 ║
║ A ║ 1 ║
║ C ║ 1 ║
╚═══════╩════════════════════╝
有人可以帮忙吗?如何编写返回此数据的SQL查询?
谢谢!
好吧,我认为需要的是MS SQL Server。
为了达到预期的结果(其中C的持续时间为1):
select
state, MIN(TimeStamp) StartsAt, EndsAt, datediff(minute,MIN(TimeStamp),EndsAt) DurationMinutes
from (
select
t1.state, t1.TimeStamp
, ISNULL(ca.EndsAt, (select max(timestamp) from table1) ) EndsAt
from table1 t1
outer apply (
select top (1) t2.timestamp as EndsAt
from table1 t2
where t1.state <> t2.state and t1.TimeStamp < t2.TimeStamp
order by t2.TimeStamp
) ca
) as derived
group by
state, EndsAt
对于数据样本,人们可能会说C的持续时间未知,因为状态尚未改变。在这种情况下,它要简单一些:
select
state, MIN(TimeStamp) StartsAt, EndsAt, datediff(minute,MIN(TimeStamp),EndsAt) DurationMinutes
from (
select
t1.state, t1.TimeStamp ,ca.EndsAt
from table1 t1
outer apply (
select top (1) t2.timestamp as EndsAt
from table1 t2
where t1.state <> t2.state and t1.TimeStamp < t2.TimeStamp
order by t2.TimeStamp
) ca
) as derived
group by
state, EndsAt
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我来说两句