SQL笔试

--Basic facts gathering
--1.
--按每辆单车的使用用户数排序，没有被使用的次数none排在最后
SELECT b.id, t.u_num
FROM bikes b
LEFT JOIN (
SELECT bike_id, COUNT(DISTINCT user_id) AS u_num
FROM trips
WHERE started_at >= '2017-06-01'
AND completed_at <= '2017-06-30' AND status = 'completed' GROUP BY bike_id ) t ON b.id = t.bike_id ORDER BY t.u_num DESC --按每辆单车的trip次数排序,没有trip的none排在最后 SELECT b.id, t.num FROM bikes b LEFT JOIN ( SELECT bike_id, COUNT(1) AS num FROM trips WHERE star

SQL笔试最先出现在Python成神之路。