Hibernate甚至在我使用Left join fetch时也会生成多个SQL查询
我对hibernate有一个有趣的问题,模型如下所示:Hibernate甚至在我使用Left join fetch时也会生成多个SQL查询,hibernate,jpa,fetch,jpql,Hibernate,Jpa,Fetch,Jpql,我对hibernate有一个有趣的问题,模型如下所示: @NamedQueries({ @NamedQuery(name = "A.test", query = "SELECT DISTINCT a FROM A a LEFT JOIN FETCH a.pk.b WHERE a.pk.b.pk.c.id = :cId AND a.pk.b.pk.d.id = :dId") }) @Entity @Table(name = "AT") public class A implements S
@NamedQueries({
@NamedQuery(name = "A.test", query = "SELECT DISTINCT a FROM A a LEFT JOIN FETCH a.pk.b WHERE a.pk.b.pk.c.id = :cId AND a.pk.b.pk.d.id = :dId")
})
@Entity
@Table(name = "AT")
public class A implements Serializable {
@EmbeddedId
private APK pk;
}
@Embeddable
public class APK implements Serializable {
@ManyToOne
@JoinColumns({@JoinColumn(name = "***", referencedColumnName = "***"),
@JoinColumn(name = "***", referencedColumnName = "***")
})
private B b;
}
@Entity
@Table(name = "BT")
public class B implements Serializable {
@EmbeddedId
private BPK pk;
}
@Embeddable
public class APK implements Serializable {
@ManyToOne
@JoinColumn(name = "***", referencedColumnName = "***")
private C c;
@ManyToOne
@JoinColumn(name = "***", referencedColumnName = "***")
private D d;
}
问题是命名查询会生成其他SQL查询。。。
有什么问题?
谢谢 默认情况下,Hibernate急切地获取多对一引用。在命名查询中选择“A”时,将解析许多多对一引用,这些引用将与您看到的SQL查询相对应。hibernate的默认行为可以通过在多对一注释上明智地放置延迟加载来覆盖,即:
@ManyToOne(fetch=FetchType.LAZY)
非常感谢。它现在正在工作。但我已经读到@ManyToOne关联中fetchtype的设置对查询没有任何影响。我想我遗漏了什么,所以我回到了手册上s