mysql - 错误代码 : 1111. 群组功能使用无效

Question

select max(postal_code) from address
where max(postal_code) 
IN (select Min(postal_code) from address
group by district
having  min(postal_code) <> "" and district <> "" );

谁能告诉我为什么会出现这个错误？

Answer 1

错误在下一行。除了 HAVING 子句

之外，您不能在 WHERE 子句中使用组函数

where max(postal_code) 

您可以尝试像下面这样修改您的查询

select max_postalcode 
from 
(
select max(postal_code) as max_postalcode,
Min(postal_code) as min_postal_code 
from address
where district is not null
group by district
having  min(postal_code) is not null
) xxx 
where max_postalcode = min_postal_code;