how many trips started from howard and ended at san fransisco
select count ( * ) from station as t1 join trip as t2 join station as t3 join trip as t4 on t1.id = t2.start_station_id and t2.id = t4.id and t3.id = t4.end_station_id where t1.city = "Howard" and t3.city = "San Fransisco"
how many trips started from south van ness and ended at san fransisco
select count ( * ) from station as t1 join trip as t2 join station as t3 join trip as t4 on t1.id = t2.start_station_id and t2.id = t4.id and t3.id = t4.end_station_id where t1.city = "South van Ness" and t3.city = "San Fransisco"
how many trips started from mountain view city and ended in palo alto city
select count ( * ) from station as t1 join trip as t2 join station as t3 join trip as t4 on t1.id = t2.start_station_id and t2.id = t4.id and t3.id = t4.end_station_id where t1.city = "Mountain View" and t3.city = "Palo Alto"