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Adrian Matei for Codever

Posted on • Originally published at codever.land

How to do a Select clause comparison of LocalDateTime in JPA

The native SQL query we want to map in JPA is similar to the following:

select *
from PARTNER
where EVENT_TIMESTAMP >= timestamp '2021-09-17 10:00:00'
  and EVENT_TIMESTAMP < timestamp '2021-09-17 11:00:00'
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where the two timestamps should come as query parameters.

With JPA you can use a TypedQuery for example and set the LocalDateTime values to query parameters via the setParameter method:

@Stateless
public class PartnerDataRepository {

    @Inject private EntityManager em;

    public List<PartnerData> findPartnerDataWithinInterval(
      LocalDateTime fromDatetime, LocalDateTime toDatetime) {
        TypedQuery<PartnerData> query =
            em.createNamedQuery(
                PartnerData.FIND_PARTNER_DATA_IN_TIME_INTERVAL, PartnerData.class);

        query.setParameter(PartnerData.FROM_DATETIME, fromDatetime);
        query.setParameter(PartnerData.TO_DATETIME, toDatetime);

        return query.getResultList();
    }
}
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In the named query itself you can directly pass the parameters before : as usual, and the implementation (in my case Hibernate) takes care of the rest :

@Entity
@Access(AccessType.FIELD)
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@Table(name = PartnerData.TABLE_NAME)
@NamedQueries({
 @NamedQuery(
      name = PartnerKerndaten.FIND_PARTNER_DATA_IN_TIME_INTERVAL,
      query = "select m from PartnerData m where eventTimestamp >= :fromDatetime and eventTimestamp < :toDatetime")
})
public class PartnerData {
  public static final String TABLE_NAME = "PARTNER";

  public static final String FROM_DATETIME = "fromDatetime";
  public static final String TO_DATETIME = "toDatetime";

  public static final String FIND_PARTNER_DATA_IN_TIME_INTERVAL =
      "findPartnerDataWithinInterval";

  //... rest ignored for brevity
}
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