TSQL-forespørgsel returnerer værdier for hver time i de seneste 24 timer

Dit problem ser ud til at være, at tidsrummet skal opdeles i timer. Så du skal starte med alle timer i døgnet. Derefter beregner du overlapningen, summerer forskellene (nedenfor i millisekunder) og konverterer alt tilbage til et tidspunkt for output.

with const as (
        select dateadd(hour, 1, cast(cast(getdate() -1 as date) as datetime)) as midnight            
    ),
    allhours as (
        select 0 as hour, midnight as timestart, dateadd(hour, 1, midnight) as timeend from const union all
        select 1 as hour, dateadd(hour, 1, midnight), dateadd(hour, 2, midnight) from const union all
        select 2 as hour, dateadd(hour, 2, midnight), dateadd(hour, 3, midnight)  from const union all
        . . .
        select 23 as hour, dateadd(hour, 23, midnight), dateadd(hour, 24, midnight) from const
    )
select ah.hour,
       sum(datediff(ms, (case when ah.timestart >= dt.begin then timestart else dt.begin end),
                        (case when ah.timeend <= dt.end then ah.timeend else dt.end end)
                   ) 
           ) as totalms,
       cast(dateadd(ms, sum(datediff(ms, (case when ah.timestart >= dt.begin then timestart else dt.begin end),
                                     (case when ah.timeend <= dt.end then ah.timeend else dt.end end)
                                    )
                           ),
                     0) as time
           ) as totalTime
from allhours ah left outer join
     DeviceTable dt
     on ah.timestart< coalesce(dt.end, getdate()) and
        ah.timeend >= dt.begin
group by ah.hour
order by ah.hour

For at få dette til at fungere, skal du også indpakke "begynd" og "slut" i dobbelte anførselstegn eller firkantede parenteser. Disse er reserverede ord i T-SQL. Og du skal erstatte "..." med ekstra linjer i timer fra 3 til 22.