MySQL / PHP - Find ledige tidsrum

SELECT a.end AS free_after
FROM bookings a
WHERE NOT EXISTS (
  SELECT 1
  FROM bookings b
  WHERE b.start BETWEEN a.end AND a.end + INTERVAL your_duration HOURS
)
AND a.end BETWEEN start_of_search_window AND end_of_search_window;

du skal blot angive værdier for your_duration (heltal), start_of_search_window (dato tid) og end_of_search_window (dato tid).

Og hvis du vil have klokker og fløjter...

SELECT free_from, free_until
FROM (
  SELECT a.end AS free_from,
  (SELECT MIN(c.start)
   FROM bookings c
   WHERE c.start > a.end) as free_until
  FROM bookings a
  WHERE NOT EXISTS (
    SELECT 1
    FROM bookings b
    WHERE b.start BETWEEN a.end AND a.end + INTERVAL your_duration HOUR
  )
  AND a.end BETWEEN start_of_search_window AND end_of_search_window
)
ORDER BY free_until-free_from
LIMIT 0,3;

Giver dig de tre korteste tilgængelige pladser (dvs. nærmest målstørrelsen) i vinduet.