MySQL table 别名无效

Question

所以我在这段代码中使用了 '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：Table '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。有什么建议吗？

Answer 1

为子查询分配别名并不意味着它可以像 table 一样对待。

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

company 是您的架构名称吗？

顺便说一句，也许您可以 return 相同的信息使用：

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;

MySQL table 别名无效

MySQL table alias does not work

mysql

sql

table-alias