我正在尝试运行一个包含 group by 子句的简单 SQL 查询。
历史实体:
@Entity
@NamedNativeQueries(value = {
@NamedNativeQuery(name = HistoryEntity.FIND_ALL_BY_REFERENCE,
query = "SELECT h.id, h.reference, h.lrn "
+ "FROM dataHistory h "
+ "WHERE h.reference = :referenceNumber OR h.lrn = :referenceNumber",
resultSetMapping = HistoryEntity.FIND_ALL_BY_REFERENCE_MAPPING),
@NamedNativeQuery(name = HistoryEntity.FIND_REFERENCE_BY_LRN,
query = "SELECT h.reference as reference "
+ "FROM dataHistory h "
+ "WHERE h.lrn = :lrn "
+ "GROUP BY h.reference",
resultSetMapping = "resultMapping")
})
@SqlResultSetMappings(value = {
@SqlResultSetMapping(name = HistoryEntity.FIND_ALL_BY_REFERENCE_MAPPING, entities = {
@EntityResult(entityClass = HistoryEntity.class, fields = {
@FieldResult(name = "id", column = "id"),
@FieldResult(name = "reference", column = "reference"),
@FieldResult(name = "lrn", column = "lrn")
})
}),
@SqlResultSetMapping(name = "resultMapping", columns = {
@ColumnResult(name = "reference")
})
})
public class HistoryEntity implements Serializable {
/**
* @param referenceNumber Referenz (LRN oder BRN)
* @param brnList Liste von BRNs
*/
public static final String FIND_ALL_BY_REFERENCE = "HistoryEntity.findAllByReference";
public static final String FIND_ALL_BY_REFERENCE_MAPPING = "HistoryEntity.findAllByReferenceMapping";
private Integer id;
private String reference;
private String lrn;
public HistoryEntity() {}
@Id
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getReference() {
return reference;
}
public void setReference(String reference) {
this.reference= reference;
}
public String getLrn() {
return lrn;
}
public void setLrn(String lrn) {
this.lrn = lrn;
}
在服务类中,我执行如下查询:
Query query = entityManager.createNamedQuery("myQuery");
query.setParameter("lrn", lrn);
List resultList = query.getResultList();
根据查询的结果,列表包含 java.lang.Character 的:
案例1:
SQL-Result(如果我在 sql 客户端中运行 sql):
|引用|
| 123456780678MMM |
| 123456781678MMM |
| 123456782678MMM |
| 123456783678MMM |
Java-List-Result(在 Java 调试 View 中):
[1,1,1,1]
案例2:
SQL 结果:
|引用|
| 123456780678MM |
Java 列表结果:
[1]
我正在寻找一种方法来运行带有标量值的简单 SQL 查询(使用 hibernate/jpa),以获取包含结果值的列表。
有没有办法在不使用标准 API 的情况下做到这一点?
如果您需要更多信息,请告诉我!
非常感谢您的帮助。
马可
最佳答案
问题是 hibernate 中的一个错误,它将结果转换为 java.lang.Character 而不是 java.lang.String。结果中仅返回每行的第一个字符。
还有一个问题更详细地描述了解决方案:
Hibernate native query - char(3) column
如果我在查询中使用强制转换函数,如下所示,它会起作用:
@NamedNativeQuery(name = HistoryEntity.FIND_REFERENCE_BY_LRN,
query = "SELECT cast(h.reference as VARCHAR(27)) as reference "
+ "FROM dataHistory h "
+ "WHERE h.lrn = :lrn "
+ "GROUP BY h.reference",
resultSetMapping = "resultMapping")
PS:我发现引用的问题已经晚了。抱歉!
关于java - 使用注释的 native hibernate/jpa 查询中标量值的问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11259749/