all flights and fares from pittsburgh to dallas round trip after 12pm less than 1100 dollars 
return flights ;return #1 from  pittsburgh ;return #2 to dallas ;return #3 that  are  round trip ;return #4 that  are  after 12pm ;return #5 that  are  less than 1100 ;return fares of  #6 ;return #6 ,  #7
['select', 'filter', 'filter', 'filter', 'filter', 'filter', 'project', 'union']