You basically have three conditions to check:
a) If start and end our both outside
b) If start is inside
c) If end is inside
Select count(*) as howmany from t1, t2 ;
where (t1.start
t2.end) ;
or (t1.start >= t2.start and t1.start<=t2.end) ;
or (t1.end >= t2.start and t1.end<=t2.end)
Costas
