What was the hottest day? Where was that?
select zip from weather where MaxTemperatureF in (select max(MaxTemperatureF) max_temp from weather);
or
select zip, date, max(MaxTemperatureF) max_temp from weather group by zip, date order by max_temp desc limit 1;

How many trips started at each station?
select start_station, count(trip_id) num_trips from trips group by start_station;

What's the shortest trip that happened?
select trip_id, duration from trips where duration in (select min(duration) from trips);

What is the average trip duration, by end station?
select end_station, round(avg(duration),2) from trips group by end_station;

