Java JPA连接查询问题
我正在试验JPA查询,但在下面的查询中不断出现错误Java JPA连接查询问题,java,jpa,Java,Jpa,我正在试验JPA查询,但在下面的查询中不断出现错误 SELECT p FROM usertype_permissions up JOIN permissions p ON up.PERMISSION_ID = p.ID WHERE up.USERTYPE_ID = 1 错误: Caused by: java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager:
SELECT p
FROM usertype_permissions up
JOIN permissions p ON up.PERMISSION_ID = p.ID
WHERE up.USERTYPE_ID = 1
错误:
Caused by: java.lang.IllegalArgumentException: An exception occurred while
creating a query in EntityManager:
Exception Description: Syntax error parsing the query
[SELECT p
FROM usertype_permissions up
JOIN permissions p ON up.PERMISSION_ID = p.ID
WHERE up.USERTYPE_ID = 1].
在JPQL中,您必须使用实体名称(默认情况下,它是Java类的名称),在我看来,
usertype\u permissions
是一个实体名称/Java类,这看起来很奇怪
看起来您使用的是表名,join后的单词必须引用类的属性,例如l.books
例如:
@Entity
public class Lib implements Serializable {
@OneToMany
private Set<Book> books;
}
@Entity
public class Book implements Serializable {
@OneToOne
private Lib lib;
}
usertype_权限不是一个类,它是由于对多关系生成的表。。。如何从该表中获取数据?我假设您有一个拥有权限对象集合的类用户,然后。。。我猜你想要一个用户的许可证?然后只需执行以下操作:从用户u中选择u.permissions,其中u.id=1
SELECT l FROM Lib JOIN l.books books