在 JPA-SQL 查询中加入集合答案

【问题标题】：Joining to a collection in a JPA-QL query在 JPA-SQL 查询中加入集合
【发布时间】：2011-10-10 02:26:58
【问题描述】：

我正在使用 JPA 进行映射，我有这个实体类

@Entity
@Table(name = "h_pe")
@XmlRootElement
@NamedQueries({

public class HPe implements Serializable {
 private static final long serialVersionUID = 1L;
 @EmbeddedId
 protected HPePK hPePK;
 @Column(name = "PE_TIMEOUT")
 private Integer peTimeout;
 @Column(name = "PE_STATUS")
 private Boolean peStatus;
 @OneToMany(cascade = CascadeType.ALL, mappedBy = "hPe")
 private Collection<HPesp> hPespCollection;
 @JoinColumn(name = "PE_ENV", referencedColumnName = "ENV_URL", insertable = false, updatable = false)
 @ManyToOne(optional = false)
 private HEnv hEnv;
 @JoinColumn(name = "PE_PLATFORM", referencedColumnName = "PLATFORM_NAME", insertable = false, updatable = false)
 @ManyToOne(optional = false)
 private HPlatform hPlatform;

}

我想写一个如下的请求JPA（我用SQl写过），我试过写但是我不明白如何使用PE_ENV，因为它是OneToMany关系的结果！

select distinct h_env.env_name,h_platform.PLATFORM_NAME
from h_env,h_platform,h_pe
where h_env.ENV_URL=h_pe.PE_ENV
and h_platform.PLATFORM_NAME=h_pe.PE_PLATFORM
and h_platform.PLATFORM_NAME='XXX';

【问题讨论】：

标签： java jpa

【解决方案1】：

Select e.name, p.name
from HPe hp join hp.hPlatform p join hp.hPespCollection p
where p.name = 'xxx'

看， http://en.wikibooks.org/wiki/Java_Persistence/Querying#Common_Queries

【讨论】：