MySQL:summera datumtider utan att räkna överlappande perioder två gånger

Ok, jag insisterar allvarligt på att du testar detta på alla sätt innan du använder det i produktionen. Testa speciellt vad som händer om det finns FLERA överlappningar under 1 tidsperiod.

Vad den här frågan gör är att beräkna varaktigheten för varje tidsintervall och hur mycket överlappning som finns med andra tidsintervall som har ett högre id.

select
    t1.id,
    t1.start_time,
    t1.end_time,
    t1.end_time - t1.start_time as duration,
    sum(
          if(t2.start_time <  t1.start_time and t2.end_time >  t1.end_time  , t1.end_time - t1.start_time, 0) -- t2 completely around t1
        + if(t2.start_time >= t1.start_time and t2.end_time <= t1.end_time  , t2.end_time - t2.start_time, 0) -- t2 completely within t1
        + if(t2.start_time <  t1.start_time and t2.end_time >  t1.start_time and t2.end_time   < t1.end_time  , t2.end_time - t1.start_time, 0) -- t2 starts before t1 starts and overlaps partially
        + if(t2.start_time <  t1.end_time   and t2.end_time >  t1.end_time   and t2.start_time > t1.start_time, t1.end_time - t2.start_time, 0) -- t2 starts before t1 ends and overlaps partially
    ) as overlap
from
    times t1
    left join times t2 on
        t2.id > t1.id --  t2.id is greater than t1.id
        and (
               (t2.start_time <  t1.start_time and t2.end_time >  t1.end_time  ) -- t2 completely around t1
            or (t2.start_time >= t1.start_time and t2.end_time <= t1.end_time  ) -- t2 completely within t1
            or (t2.start_time <  t1.start_time and t2.end_time >  t1.start_time) -- t2 starts before t1 starts and overlaps
            or (t2.start_time <  t1.end_time   and t2.end_time >  t1.end_time  ) -- t2 starts before t1 ends and overlaps
        )
group by
    t1.id

Så vad du vill ha i slutändan är detta:

select
    sum(t.duration) - sum(t.overlap) as filtered_duration
from
    (
        OTHER QUERY HERE
    ) as t

Så till slut har du den här frågan:

select
    sum(t.duration) - sum(t.overlap) as filtered_duration
from
    (
        select
            t1.id,
            t1.start_time,
            t1.end_time,
            t1.end_time - t1.start_time as duration,
            sum(
                  if(t2.start_time <  t1.start_time and t2.end_time >  t1.end_time  , t1.end_time - t1.start_time, 0) -- t2 completely around t1
                + if(t2.start_time >= t1.start_time and t2.end_time <= t1.end_time  , t2.end_time - t2.start_time, 0) -- t2 completely within t1
                + if(t2.start_time <  t1.start_time and t2.end_time >  t1.start_time and t2.end_time   < t1.end_time  , t2.end_time - t1.start_time, 0) -- t2 starts before t1 starts and overlaps partially
                + if(t2.start_time <  t1.end_time   and t2.end_time >  t1.end_time   and t2.start_time > t1.start_time, t1.end_time - t2.start_time, 0) -- t2 starts before t1 ends and overlaps partially
            ) as overlap
        from
            times t1
            left join times t2 on
                t2.id > t1.id --  t2.id is greater than t1.id
                and (
                       (t2.start_time <  t1.start_time and t2.end_time >  t1.end_time  ) -- t2 completely around t1
                    or (t2.start_time >= t1.start_time and t2.end_time <= t1.end_time  ) -- t2 completely within t1
                    or (t2.start_time <  t1.start_time and t2.end_time >  t1.start_time) -- t2 starts before t1 starts and overlaps
                    or (t2.start_time <  t1.end_time   and t2.end_time >  t1.end_time  ) -- t2 starts before t1 ends and overlaps
                )
        group by
            t1.id
    ) as t