没有直接连接的Hibernate连接查询

Question

我有以下实体 class

public class Customer {
    @Id
    private int id;
    @Column(name = "CID")
    private String cid;
}


public class Alccs {
    @Id
    private int vid;
//    @Column(name = "CID")
//    private String cid;

    @ManyToOne
    @JoinColumn(name = "CID", referencedColumnName = "CID")
    private Customer customer;
}


public class Rtwo {
    @Id
    private int jobNo;

    @ManyToOne
    @JoinColumn(name = "CID", referencedColumnName = "CID")
    private Customer customer;
}




public class RTwoCycle {
    @Id
    private int cycleJobNo;
    @Column
    private int vid;

    @ManyToOne
    @JoinColumn(name = "JobNo", referencedColumnName = "JobNo")
    private TblRtwo tblRtwo;

}

如何使用 HQL 和 criteria

编写如下查询

select top 20 * from RTwoCycle rtCycle join Alccs al on rtCycle.vid = al.vid;

对于 HQL，我尝试了以下方法

from TBLRTwoCycle rtCycle join TBLAL al on rtCycle.vid = al.vid

但收到 QuerySyntaxException: Path expected for join! 错误

关于标准我不知道该怎么做

如何做到这一点？？

Answer 1

早于 5.1 的 JPA 和 Hibernate 版本需要定义的关系才能在 JPQL 查询中连接两个实体。这通常会导致级联 JOIN 语句遍历实体之间的关系图，或声明如果实体之间没有关系，则 JPQL 无法实现实体的 JOIN。

Hibernate 5.1 引入了对不相关实体的显式连接。语法与 SQL 非常相似，允许您在 ON 语句中定义 JOIN 条件。

More Info

Answer 2

from RTwoCycle as rtCycle inner join Alccs as al with rtCycle.vid = al.vid

Answer 3

对于 HQL 简单的连接和 on clause 就足够了

from table1 as t1 inner join table2 as t2 on t1.vid=t2.vid

或

from table1 as t1, table2 as t2 where t1.vid=t2.vid

标准Restriction.sqlRestriction是这个问题的解决方案

session.createCriteria(Class1,"c1")
        .createAlias("class2", "c2")
        .add(Restrictions.sqlRestriction("c1.vid=c2.vid")

没有直接连接的Hibernate连接查询

Hibernate join query without direct connection

hibernate

hql

criteria