JPA 命名查询

Question

嘿，我是 JPA 的新手，对 SQL 还很陌生，我需要编写一个选择查询

我需要：

“选择金额大于所有美元付款平均值的所有付款”

我有一个 JPA 实体：

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

我试过了：

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

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.

谁能指出我正确的方向。

Answer 1

使用

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

您的子查询是

SELECT AVG(x.amount) from Payment

，而x 未定义。