1

所以我在这段代码中使用'as'命令

select PERSONAL_ID,NAME,SURNAME,BIRTH_DATE,NUMBER_OF_ORDERS  
from(
select PERSONAL_ID,NAME,SURNAME,BIRTH_DATE,count(CUSTOMER_ID) as NUMBER_OF_ORDERS
from customer as C
right join
customer_hotel as CH on CH.CUSTOMER_ID = C.ID
group by(CH.CUSTOMER_ID)
) as O
where NUMBER_OF_ORDERS = (select max(NUMBER_OF_ORDERS) from O);

它说：表'company.o'不存在。但是当我这样做时

select PERSONAL_ID,NAME,SURNAME,BIRTH_DATE,NUMBER_OF_ORDERS  
from(
select PERSONAL_ID,NAME,SURNAME,BIRTH_DATE,count(CUSTOMER_ID) as NUMBER_OF_ORDERS
from customer as C
right join
customer_hotel as CH on CH.CUSTOMER_ID = C.ID
group by(CH.CUSTOMER_ID)
) as O
where NUMBER_OF_ORDERS = (select max(NUMBER_OF_ORDERS) 
from(
select PERSONAL_ID,NAME,SURNAME,BIRTH_DATE,count(CUSTOMER_ID) as NUMBER_OF_ORDERS
from customer as C
right join
customer_hotel as CH on CH.CUSTOMER_ID = C.ID
group by(CH.CUSTOMER_ID)
) as O);

它工作正常。有什么建议么？

4

1 回答 1

1

为子查询分配别名并不意味着它可以完全像表一样对待。

在第一个查询中，mysql 无法知道Oinselect max(NUMBER_OF_ORDERS) from O不是表。所以这就是它对待它的方式，因此是错误的。

是company您的架构的名称吗？

顺便说一句，也许您可​​以使用以下方法返回相同的信息：

select PERSONAL_ID,NAME,SURNAME,BIRTH_DATE,count(CUSTOMER_ID) as NUMBER_OF_ORDERS
from customer as C
right join
customer_hotel as CH on CH.CUSTOMER_ID = C.ID
group by(CH.CUSTOMER_ID)
order by count(CUSTOMER_ID) desc
limit 1;
于 2016-11-04T16:42:55.960 回答