select city,max(money) from user,card where user.userId=card.userId group by city;
select userId from (select city,max(money) a from user,card where user.userId=card.userId group by city) c,card where a=card.money;
select city,name ,a from (select userId,a from (select city,max(money) a from user,card where user.userId=card.userId group by city) c,card where a=card.money) y,user where user.userId=y.userId ;