select Trips.Request_at as Day,
round(sum(if(Trips.Status='completed',0,1))/count(Trips.Status),2) as 'Cancellation Rate'
from Trips
join Users
on Trips.Client_Id=Users.Users_id
where Users.Banned='No' and
Trips.Request_at between '2013-10-01' and '2013-10-03'
group by Trips.Request_at`
Subquery returns more than 1 row
意思是指子查询的结果多于一行。WHERE ( SELECT cc.ipFROM crawl_site cc WHERE cc.id=this_.site_id)>=_ip.start_ip用这种条件,(SELECT。。。) 里面结果只能1条,多了就会“Subquery returns more than 1 row”