对于我的生活,我无法弄清楚如何构建这个 JPA 查询。
我需要找到未在给定 SyncSendingConfig 下传输的 TransactionLogs,按 ID 排序。
在 SO 上进行研究,我认为应该可以在 SQL 中进行外连接,其中一侧的 ID 为空,如下图所示:
这是我必须与之合作的实体。@Entity
public class SyncSendingConfig {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private long id;
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "sendingConfig")
private Set<SyncJob> sendJobs = new HashSet<>();
}
@Entity
public class SyncJob {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private long id;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "sending_config_id")
private SyncSendingConfig sendingConfig;
@ManyToMany(cascade = { CascadeType.ALL })
@JoinTable(
name = "SyncJob_TransactionLog",
joinColumns = { @JoinColumn(name = "sync_job_id") },
inverseJoinColumns = { @JoinColumn(name = "transaction_log_id") }
)
private Set<TransactionLog> transmitted = new HashSet<>();
}
@Entity
public class TransactionLog {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private long id;
@ManyToMany(mappedBy = "transmitted")
private Set<SyncJob> syncJobs = new HashSet<>();
}
我正在尝试编写的 DAO:public interface SyncSendingConfigDao extends JpaRepository<SyncSendingConfig, Long> {
// TODO: This is the query I'm trying to get to work
/** Returns those transactions that were never sent for the given SyncSenderConfig, ordered by ID */
@Query("SELECT tl FROM SyncJob sj "+
"JOIN SyncSendingConfig ssc ON sj.sendingConfig = ssc.id AND ssc.id= :sendingConfigId "+
"RIGHT JOIN TransactionLog tl on tl.syncJobs = sj "+
"WHERE sj.id is null"
)
Stream<TransactionLog> findTransactionsNotSentForSyncSendingConfigId(@Param("sendingConfigId") long sendingConfigId);
// If this part is relevant, this join shows how I can get only those SyncJobs which are related to the SyncSendingConfig of interest
@Query("SELECT sj FROM SyncJob sj JOIN SyncSendingConfig ssc ON sj.sendingConfig = ssc.id WHERE ssc.id= :sendingConfigId ")
@QueryHints(value = @QueryHint(name = org.hibernate.jpa.QueryHints.HINT_FETCH_SIZE, value = "500"))
Stream<SyncJob> findJobs(@Param("sendingConfigId") long sendingConfigId);
}
上面关于 DAO 的查询显示了我正在尝试做的事情。我真的不确定如何将 SQL 转换为 JPQL ......尤其是在连接条件和顺序上。
更新:
这是我正在尝试翻译的确切 SQL 查询。它匹配 hibernate 在上面的类中定义的所有关系。select tl.*
from sync_job sj
join sync_sending_config ssc
on ssc.id = sj.sending_config_id and ssc.id=2
join sync_job_transaction_log sjtl
on sjtl.sync_job_id = sj.id
RIGHT JOIN transaction_log tl
on tl.id = sjtl.transaction_log_id
where sjtl.sync_job_id is null
当直接运行此查询时,它会返回正在寻找的确切结果。
如果有人可以提供帮助,我将不胜感激。我一直在靠墙试图弄清楚 JPQL 语法。
谢谢
更新 2
使用“@S B”后,似乎 JPQL 不支持右连接。由于没有找到如何使用左连接(如果可能)在 JPQL 中编写此内容,我使用了 native 查询:@Query(value = "select tl.* from sync_job sj "+
"join sync_sending_config ssc on ssc.id = sj.sending_config_id and ssc.id = :sendingConfigId "+
"join sync_job_transaction_log sjtl on sjtl.sync_job_id = sj.id "+
"RIGHT JOIN transaction_log tl on tl.id = sjtl.transaction_log_id "+
"where sjtl.sync_job_id is null",
nativeQuery = true)
@QueryHints(value = @QueryHint(name = org.hibernate.jpa.QueryHints.HINT_FETCH_SIZE, value = "500"))
Stream<TransactionLog> findTransactionsNotSentForSyncSendingConfigId(@Param("sendingConfigId") long sendingConfigId);
最佳答案
假设以下虚拟数据设置:
TransactionLogs
1
和 2
根据 sync_job_transaction_log 表中的映射在 SyncSendingConfig ID 1
下传输。因此,在 SyncSendingConfig ID
1
下传输的 TransactionLogs 而不是 将是 3
和 4
。因此,为了找到在给定的 SyncSendingConfig 下尚未传输的 TransactionLogs,对应的 JPQL 是 -
@Query("select t from TransactionLog t where t not in (" +
"select t1 from TransactionLog t1 join t1.syncJobs tsj where tsj in "
+ "(select sj from SyncJob sj where sj.sendingConfig.id = :sendingConfigId)"
+ ")")
将 JPQL 视为应用于 Java 对象的 SQL,实体表示表,属性表示列,has-a 关系表示映射关系。
现在,当您要连接两个表时,只需引用相应的实体,只要正确指定了连接列,就会在连接表和列上正确形成 SQL 查询。
示例 SQL -
select column(s) from table1 <type of> join table2 on table1.column1 = table2.column1 where <filter conditions here>
对应的 JPQL 设置 -
Entity1 (corresponds to table1) ->
property1 (corresponds to column)
property2 (corresponds to mapping relationship, has @JoinColumn details)
上述设置的 JPQL -
select property1 from entity1 <type of> join entity1.property2 where <filter condition here>
在评论中讨论后更新 -
由于无法在当前设置中正确连接,建议根据性能参数评估 JPQL,或者将工作 SQL 用作 nativeQuery。
@Query(value = "select tl.* from sync_job sj "+
"join sync_sending_config ssc on ssc.id = sj.sending_config_id "+
"join sync_job_transaction_log sjtl on sjtl.sync_job_id = sj.id "+
"RIGHT JOIN transaction_log tl on tl.id = sjtl.transaction_log_id "+
"where sjtl.sync_job_id is null and ssc.id = :sendingConfigId",
nativeQuery = true)
关于sql - 如何编写 JPQL 查询以查找此连接中未找到的记录?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/59910507/