我想知道JPQL是否可以嵌套查询。我正在研究Spring Data JPA,并且还上传了一些相关问题。
如果我在MySQL中使用sql以下的代码,该如何生成JPQL:
select
c.*
from
cheat c
left join (select * from cheat_vote where val = 1) v on c.cheat_seq = v.cheat_fk
group by
c.cheat_seq
having
count(*) < 10
limit 5
我有两个实体。
public class Cheat implements Serializable{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "cheat_seq", length = 10)
private Long cheatSeq;
@Column(name = "question", unique = true, nullable = false)
private String question;
@Column(name = "answer", unique = true, nullable = false)
private String answer;
@Column(name = "writer_ip", nullable = false)
private String writerIP;
@Temporal(TemporalType.TIMESTAMP)
@Column(name = "reg_date", nullable = false)
private Date regDate;
@Transient
private String regDateText;
@OneToMany(mappedBy = "cheat", fetch=FetchType.LAZY)
private Set<CheatVote> vote;
@Override
public String toString() {
return "Cheat [cheatSeq=" + cheatSeq + "]";
}
}
上面的实体有一个@OneToMany集合,该集合实体在下面。
public class CheatVote implements Serializable{
private static final long serialVersionUID = 1L;
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Id
@Column(name="seq", nullable=false)
private Long seq;
@Column(name="val", nullable=false)
@NonNull
private Integer value;
@Column(name="ip_address", nullable=false)
@NonNull
private String ipAddress;
@JoinColumn(name="cheat_fk", referencedColumnName="cheat_seq")
@ManyToOne(cascade=CascadeType.ALL, fetch=FetchType.LAZY)
@NonNull
private Cheat cheat;
@Override
public String toString() {
return "CheatVote [seq=" + seq + "]";
}
}
我想获得包含少于10个子代CheatVote实体的Cheat实体。
答案 0 :(得分:0)
您可以尝试:
@Query("SELECT c FROM Cheat c LEFT JOIN c.vote v WHERE v.value = 1 GROUP BY c.cheatSeq HAVING count(c) < 10")
关于'LIMIT',您可以使用Spring Data JPA的参数Pageable