根据教材中的user表、card表、transInfo表进行多表查询

完成以下功能；

1. 查询展示交易时间、银行卡号、客户姓名、交易类型、交易金额
2. 查询交易次数最多的银行卡信息
3. 查询交易次数最多的客户信息
   
4. 统计每个银行卡的交易金额，展示银行卡号、银行卡余额，交易总金额
5. 统计每个客户的交易次数，展示客户姓名、交易次数
6. 统计每个客户的交易金额，展示客户姓名、交易金额，按交易金额降序排列
7. 查询北京地区2019年7月的总交易金额
8. 查询哪个城市消费总金额最大（消费：支取和转出）
9. 查询哪个城市最不爱花钱

select transinfo.transDate,card.cardNo,user.`name`,transinfo.type,transinfo.money from user,card,transinfo where user.userId=card.userId and card.cardNo=transinfo.cardNo;

-- 嵌套

select card.*,count(transinfo.cardNo) c from card,transinfo WHERE card.cardNo=transinfo.cardNo GROUP BY card.cardNo  ORDER BY c desc limit 0,1;

-- 嵌套做

select card.cardNo,card.money,sum(transinfo.money) from card,transinfo WHERE card.cardNo=transinfo.cardNo GROUP BY card.cardNo;

select name,count(card.cardNo) from user, card,transinfo where user.userId=card.userId and card.cardNo=transinfo.cardNo GROUP BY card.cardNo;

select name,SUM(transinfo.money) s from user,card,transinfo where user.userId=card.userId and card.cardNo=transinfo.cardNo   GROUP BY card.cardNo order by s desc;

select city,sum(transinfo.money) from user,card,transinfo where user.city='北京' and transinfo.transDate LIKE'2019-07%' and user.userId=card.userId and card.cardNo=transinfo.cardNo

select city,sum(transinfo.money) s from user,card,transinfo where transinfo.type='支取' or transinfo.type='转出' and user.userId=card.userId and card.cardNo=transinfo.cardNo GROUP BY city order by s desc;

select city,sum(transinfo.money) s from user,card,transinfo where transinfo.type='支取' or transinfo.type='转出' and user.userId=card.userId and card.cardNo=transinfo.cardNo GROUP BY city order by s ;