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));

我有以下查询：列出所有客户租用DVD的数量和名称，而不是所有客户目前雇用的平均DVD数量。

我确定这应该涉及嵌套查询，但我不确定从哪里开始？

我试过了：

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

但收到此错误消息：ORA-00934：此处不允许组功能

Answer 1

试试这个

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

Answer 2

2种方式......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);

ORACLE SQL查询 - AVG

2 个答案: