180. 连续出现的数字

想不出来，一看题解就懂

select distinct l1.num ConsecutiveNums
from logs l1,logs l2, logs l3
where 
l1.id = l2.id - 1 
and l2.id = l3.id - 1
and l1.num = l2.num 
and l2.num = l3.num