Question

我正在尝试使用JPA查询，但在以下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: 

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].

Answer 1

在JPQL中你必须使用实体名称（默认情况下它是Java类的名称），对我来说，usertype_permissions是实体名称/ Java类看起来很奇怪......

看起来您正在使用表名，并且连接后的单词必须引用类的属性，例如l.books

示例：

@Entity
public class Lib implements Serializable {
      @OneToMany
      private Set<Book> books;
}

@Entity
public class Book implements Serializable {
      @OneToOne
      private Lib lib;
}

JPQL查询如下所示：

SELECT l FROM Lib JOIN l.books books

JPA JOIN查询问题

1 个答案: