JPA命名查询

Question

Hey I'm new to JPA and fairly new to SQL and I need to write a slection query 嘿，我是JPA的新手，对SQL很新，我需要编写一个选择查询

I need to : 我需要：

"Select all payments where the amount is more than the average value of all USD payments" “选择金额超过所有美元付款平均价值的所有付款”

I have a JPA entity : 我有一个JPA实体：

@Id
@GeneratedValue(strategy = GenerationType.TABLE)
private Long id;
private String account;
private double amount;
private String currency;

I tried with : 我尝试过：

@NamedQuery(name="payByUSD" , query="SELECT x FROM Payment x WHERE x.amount > (SELECT AVG(x.amount)from Payment)")

but I got the following error: 但我收到以下错误：

- The FROM clause must defined at least one identification variable declaration.
- The right expression is missing from the arithmetic expression.

Can anyone point me in the right direction. 任何人都可以指出我正确的方向。

Answer 1

Use 使用

SELECT x FROM Payment x 
WHERE x.amount > (SELECT AVG(p.amount) from Payment p)

Your subquery is 你的子查询是

SELECT AVG(x.amount) from Payment

, and x is not defined. ， x未定义。