show me all flights from pittsburgh to boston both direct and connecting that depart pittsburgh after 7pm 
return flights ;return #1 from  pittsburgh  ;return #2 to boston ;return #3 that  depart pittsburgh  after 7pm ;return #4 that  are direct ;return #4 that  are connecting ;return #5 , #6
['select', 'filter', 'filter', 'filter', 'filter', 'filter', 'union']