ORACLE SQL查询 - AVG

Question

所以，我有以下Oracle SQL数据库表：

create table Customer 
(customerID char(25) not null, 
name char(50), 
address char(100), 
dateRegistered DATE, 
noOfDvdHiring int, 
primary key (customerID)); 

而且我有以下查询：列出谁是比一般的雇佣更多的DVD所有客户的唯一号码和名字的DVD目前由所有客户雇用。

我敢肯定，这应该涉及嵌套查询，但我不确定从哪里开始？

我曾尝试：

SELECT customerID, name 
FROM Customer 
WHERE noOfDvdHire > AVG(noOfDvdHire); 

但收到此错误信息：ORA-00934：组函数是不是在这里

Answer 1

允许试试这个

SELECT customerID, name 
FROM Customer 
WHERE noOfDvdHiring > (select AVG(noOfDvdHiring) from customer); 

Answer 2

2种方式的...区别在于执行计划

select * from (
    select customer_id, noOfDvdHire, avg(noOfDvdHire) over() avgg from Customer 
) where noOfDvdHire > avgg 

select customer_id, noOfDvdHire from Customer 
    where noOfDvdHire > (select AVG(noOfDvdHire) from customer);