ORACLE SQL查詢 - AVG

Question

所以，我有以下Oracle SQL數據庫表：

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

而且我有以下查詢：列出誰是比一般的僱傭更多的DVD所有客戶的唯一號碼和名字的DVD目前由所有客戶僱用。

我敢肯定，這應該涉及嵌套查詢，但我不確定從哪裏開始？

我曾嘗試：

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

但收到此錯誤信息：ORA-00934：組函數是不是在這裏

Answer 1

允許試試這個

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

Answer 2

2種方式的...區別在於執行計劃

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);