我正在为下表寻找合适的 JPQL 查询，以便它可以在 Java 代码中工作，它不应该是本机查询

Question

下面是我无法进行正确 JPQL 查询的表架构

Mobile table     | hardware table       |  releases table
--------------------------------------------------------------
id pk            |   id  pk            | id  pk
name varchar         size  varchar       launchdate varchar
hardware_id fk   |   pdname varchar    | tally  varchar
releases_id fk   |                     | 
i have tried all below query's in my code but it all gives error for:
//String qry="Select m.name,h.size,h.pdname from com.example.users.Mobile m, 
com.example.users.entities.Hardware h where m.hardware_id=h.id ";

//String qry="Select m from Mobile m inner join fetch m.hardware h where m.hardware_id=h.id";
//String qry = "SELECT m FROM Mobile m JOIN m.hardware_id h WHERE m.hardware_id = h.id";
String qry="select m.name from mobile m,hardware h where m.hardware_id=h.id";

System.out.println("in entity manager Query is "+ qry);
Query query = entityManager.createQuery(qry);
return query.getResultList();

错误：org.hibernate.hql.internal.ast.QuerySyntaxException：移动未映射

This is what i have in Mobile Entity
@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name ="hardware_id",referencedColumnName = "id")
private Hardware hardware;
@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name="releases_id",referencedColumnName = "id")
private Releases releases;

Answer 1

您在@JoinColumn中指定的名称是数据库列，而不是实体属性名称。 问题是您混合了属性和列名称。

查询：

"SELECT m FROM Mobile m JOIN Hardware h ON m.hardware.id = h.id"

Answer 2

您在Mobile实体中有这样的属性吗？

@ManyToOne(optional = false)
@JoinColumn(name = "hardware_id")
private Hardware hardware;