If all vehicles have a single boat secured to the roof.
return vehicles ;return boats ;return roof of #1 ;return #2 that are secured to  #3 ;return number of  #4 for each  #1 ;return #1 where  #5 is equal to  one ;return number of  #1 ;return number of  #6 ;return if  #7 is equal to  #8
['select', 'select', 'project', 'filter', 'group', 'comparative', 'aggregate', 'aggregate', 'boolean']