在没有直接连接的情况下休眠加入查询

Question

>我有以下实体类

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编写如下所示的查询

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

对于 HQL，我尝试遵循

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

但是得到QuerySyntaxException: Path expected for join!错误

关于我不知道该怎么做的标准

怎么做？？

Answer 1

早于 5.1 的 JPA 和 Hibernate 版本需要定义的关系才能在 JPQL 查询中联接两个实体。这通常会导致级联 JOIN 语句遍历实体之间的关系图，或者如果实体之间没有关系，则无法使用 JPQL 对实体进行 JOIN 的语句。

Hibernate 5.1 在不相关的实体上引入了显式连接。该语法与 SQL 非常相似，允许您在 ON 语句中定义 JOIN 条件。

更多信息

Answer 2

1. 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

对于标准Restriction.sqlRestriction是此问题的解决方案

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