如何在两个表（联接表）上使用休眠查询？

Question

I have these tables: cont(id_cont, user, pass) emp(emp_id, name, cont_id_cont (fk))

 @Entity @Table(name = "emp", catalog = "", uniqueConstraints = { @UniqueConstraint(columnNames = "cont_id_cont") }) public class Emp implements java.io.Serializable{ private int id_emp; private ContUser contUser; private String name; 

and

@Entity
@Table(name = "cont", catalog = "", uniqueConstraints = {
        @UniqueConstraint(columnNames = "pass") })
public class Cont implements java.io.Serializable{

    private int id_cont;
    private String user;
    private String pass;
private Set<Emp> empForCont = new HashSet<Emp>(0);
}

Now: I want this query: select cont.user, emp.name, emp.cont_id_cont from cont inner join emp on cont.id_cont= emp.cont_id_cont where cont.user = 'gbs04405';

Answer 1

This style of accessing data is not what ORM is intended for. If you are using Hibernate , you should (usually) access data through objects. To make this work, instead of embedding SQL like constraints, define relations @OneToMany , @ManyToOne , and/or @ManyToMany between objects where necessary.

In addition, you should consider using HQL (or JPQL ) instead of pure SQL , to achieve what you want.

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It should be something like this:

SELECT e FROM Emp e JOIN e.contUser u WHERE u.user = :userstring

You can check here for further JPQL syntax.