sql - 最大子查询

Question

select substr(phone,0,3) as area_code
from customer
where (select max(count(area_code)) 
         from customer);

为什么这里有错误？怎么修？它说缺少表达..

标签： sql

Answer 1

整个select max() ...部分返回一个值，但在whereclausule 之后你应该有类似where something = 1. 我只能猜测你想用这个查询实现什么，但它可能应该是这样的：

select substr(phone,0,3) as area_code from customer 
where area_code in (select max(substr(phone,0,3)) from customer);

PS看这里