database/_603.sql

--603. Consecutive Available Seats
--
--Several friends at a cinema ticket office would like to reserve consecutive available seats.
--Can you help to query all the consecutive available seats order by the seat_id using the following cinema table?
--
--| seat_id | free |
--|---------|------|
--| 1       | 1    |
--| 2       | 0    |
--| 3       | 1    |
--| 4       | 1    |
--| 5       | 1    |
--Your query should return the following result for the sample case above.
--| seat_id |
--|---------|
--| 3       |
--| 4       |
--| 5       |
--Note:
--The seat_id is an auto increment int, and free is bool ('1' means free, and '0' means occupied.).
--Consecutive available seats are more than 2(inclusive) seats consecutively available.

select c.seat_id from cinema c where c.free = 1
and
(
    c.seat_id+1 in (select seat_id from cinema where free=1)
    or
    c.seat_id-1 in (select seat_id from cinema where free=1)
)
order by c.seat_id