Question

所以我正在使用＆＃39;作为＆＃39;此代码中的命令

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＆＃39; company.o＆＃39;不存在。但是当我这样做的时候

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);

它运作正常。有什么建议吗？

Answer 1

为子查询指定别名并不意味着它可以像表一样处理。

在第一个查询中，mysql无法知道O中的select max(NUMBER_OF_ORDERS) from O不是表。这就是它如何对待它，因此错误。

company是您架构的名称吗？

顺便说一句，也许您可以使用以下方式返回相同的信息：

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;

MySQL表别名不起作用

1 个答案: