I have a SQL query like this:
SELECT h.name, h.created_date, tbl.*
FROM my_table tbl
LEFT JOIN
(SELECT name, max(created_date) created_date FROM my_table GROUP BY name) h
ON tbl.name = h.name;
It returns the row from my_table (which has multiple for name="") along with the maximum created_date for that name.
Is there a way to replicate this in a JPQL query?
Here is the gist of the Entity class, it's quite simple:
#Entity
#Table(name = "MY_TABLE")
#XmlRootElement
public class MyTable implements Serializable {
private BigDecimal tableId;
private String name;
private Date createdDate;
// ...
#Id
#Basic(optional = false)
#Column(name = "TABLE_ID")
#GeneratedValue(generator = "TBL_ID_SEQ")
public BigDecimal getTableId() {
return tableId;
}
#Basic(optional = false)
#Column(name = "NAME")
public String getName() {
return name;
}
#Basic(optional = false)
#Column(name = "CREATED_DATE", insertable = false)
#Temporal(TemporalType.TIMESTAMP)
public Date getCreatedDate() {
return createdDate;
}
// ... getters/setters
}
Just reading your question I guess you do not need another entity. Entities in JPA are the same like tables in SQL. Usually there is a 1:1 relationship between entities and tables. You just have to know how to invoke a query using JPQ. You need a entity manager, which invokes your statement.
EntityManagerFactory emf = Persistence.createEntityManagerFactory("PersistenceUnit");
EntityManager em = emf.createEntityManager();
You have to define your persistence unit, i.e. in a pom file, or a config java file. So done you can go on coding something like this:
Query q = em.createQuery( "Your query in sql syntax as a string object" );
In respect to your entities and invoked query you will receive a List using
List<object> resultOfMyQuery = q.getResultList();
This is only one short example. But hopefully you got some buzzwords to look for ;)
Related
I'm trying to implement a custom #loader using a namedQuery on a OneToOne - Relation of an entity.
However the lastDatalog field remains null at all given times
I've tested the named query befor on a simple integration test using a repositry, the result was exactly what I intend to have in the lastDestinationStatus
(I need the last updated record from the logs for this data and IREF combination)
when I query the Datalog entity with the id of the data I get the correct result so the Datalog entity seems to be persisted
maybe good to know : curent hibernate version on the project is 4.2.11.Final
this is en extract from entity 1
#Entity
#Table(name = "data")
#NamedQueries({
#NamedQuery(name = "LastLogQuery", query = "select log from DataLog log where log.data.id= ?1 and " +
"log.IREF = (select max(log2.IREF) from DataLog log2 where log2.data = log.data ) " +
"and log.tsUpdate = (select max(log3.tsUpdate) from DataLog log3 where log3.data = log.data and log3.IREF = log.IREF)")})
public class Data{
....
#OneToOne(targetEntity = DataLog.class)
#Loader(namedQuery = "LastLogQuery")
private DataLog lastDataLog;
}
extract from entity 2
#Entity
#Table(name ="log")
public class DataLog{
.......
#ManyToOne(fetch = FetchType.EAGER)
#org.hibernate.annotations.Fetch(value = org.hibernate.annotations.FetchMode.SELECT)
#JoinColumn(name = "DTA_IDN", nullable = false)
private Data data;
/** IREF */
#Column(name = "DSE_LOG_UID_FIL_REF_COD")
private String IREF;
#Column(name = "LST_UPD_TMS", nullable = false)
#Temporal(TemporalType.TIMESTAMP)
private Date tsUpdate;
}
I have 2 entities CallRecords and CallRecordOperators with one-to-many relation as given below
public class CallRecords {
#Id
#Column(name = "id", unique = true)
private String id;
#Column(columnDefinition = "varchar(255) default ''")
private String callerNumber = "";
#OneToMany(mappedBy="callrecord")
private List<CallRecordOperators> callRecordOperators = new ArrayList<CallRecordOperators>();
//getter setters
}
public class CallRecordOperators {
#Id
#Column(name = "id", length = 50, unique = true, nullable = false, insertable = false, updatable = false)
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#JsonIgnore
#ManyToOne
#JoinColumn(name = "callRecordId")
private CallRecords callrecord;
#ManyToOne
#JoinColumn(name = "operatorId")
private Operator operator;
#Formats.DateTime(pattern = "yyyy-MM-dd HH:mm:yy")
#Column(columnDefinition = "TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP")
private Date startTime = new Date();
#Column(columnDefinition = "varchar(100) default ''")
private String dialStatus;
//getter setter
}
So if the user ask for all "CallRecords" data I also have to give "CallRecordOperators" as they are related.
Current code for Mapper and DTOs
#Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
public interface CallRecordsMapper {
CallRecordsMapper INSTANCE = Mappers.getMapper(CallRecordsMapper.class);
#Mapping(source="callRecordOperators",target = "operators")
CallRecordsDto callRecordsToCallRecordsDto(CallRecords callRecords);
public abstract CallRecordOperatorsDto toTarget(CallRecordOperators source);
List<CallRecordsDto> callRecordsToCallRecordsDtos(List<CallRecords> callRecords);
}
public class CallRecordsDto {
private String callerNumber;
private List<CallRecordOperatorsDto> operators;
//getter setters
}
public class CallRecordOperatorsDto {
private String callRecordsId;
private String operatorId;
private String operatorName;
private String currentTime;
// getter setter
}
But for above code I am getting
{
"callerNumber": "9898989898",
"operators": [{
"callRecordsId": null,
"operatorId": null,
"operatorName": null,
"currentTime": null
}, {
"callRecordsId": null,
"operatorId": null,
"operatorName": null,
"currentTime": null
}]
}
the values of operator array are null. what could be he issue?
It seems your are lacking the mappings from CallRecordOperators to CallRecordOperatorsDto:
#Mapper
public interface CallRecordsMapper {
CallRecordsMapper INSTANCE = Mappers.getMapper(CallRecordsMapper.class);
#Mapping(source="callRecordOperators",target = "operators")
CallRecordsDto callRecordsToCallRecordsDto(CallRecords callRecords);
#Mapping(target = "callRecordsId", source = "callrecord.id")
#Mapping(target = "operatorId", source = "operator.id")
#Mapping(target = "operatorName", source = "operator.name")
#Mapping(target = "currentTime", source = "startTime")
CallRecordOperatorsDto callRecordOperatorsToDto(CallRecordOperators source);
}
When you do a Hibernate query of A elements, you can fetch the related B elements of the bs collection using different strategies. Some of them are:
If you use HQL to construct your queries, you can do a JOIN FETCH or LEFT JOIN FETCH to populate the bs collection:
String hql = "SELECT DISTINCT a FROM " + A.class.getName()
+ " a LEFT JOIN FETCH a.bs WHERE ...";
This query will load all data using a single SQL query.
Use eager fetching of the bs collection, changing the #OneToMany annotation:
#OneToMany(fetch=FetchType.EAGER)
private List<B> bs;
In this case, when you run a query of A elements, a SQL query will be launched to retrieve the A data, and for each A object in the result, a SQL query will be executed to load the corresponding bs collection.
If you use Criteria to build the query, you can change the fetch mode of the bs collection in a way similar to the HQL JOIN FETCH:
Criteria c = session.createCriteria(A.class);
c.setFetchMode("bs", FetchMode.JOIN);
c.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
How about switching to a slightly different approach that also performs better? By using Blaze-Persistence Entity Views you can define your mapping directly on the DTO classes and apply that onto a query builder to generate efficient queries that perfectly fit your DTO structure.
#EntityView(CallRecords.class)
public interface CallRecordsDto {
// The id of the CallRecords entity
#JsonIgnore
#IdMapping("id") String getId();
String getCallerNumber();
#Mapping("callRecordOperators")
List<CallRecordOperatorsDto> getOperators();
}
#EntityView(CallRecordOperators.class)
public interface CallRecordOperatorsDto {
// The id of the CallRecordOperators entity
#JsonIgnore
#IdMapping("id") Long getId();
#Mapping("callrecord.id")
String getCallRecordId();
#Mapping("operator.id")
String getOperatorId();
#Mapping("operator.name")
String getOperatorName();
#Mapping("startTime")
String getCurrentTime();
// Whatever properties you want
}
See how you can map the entity attributes right in your DTOs? And here comes the code for querying
EntityManager entityManager = // jpa entity manager
CriteriaBuilderFactory cbf = // query builder factory from Blaze-Persistence
EntityViewManager evm = // manager that can apply entity views to query builders
CriteriaBuilder<User> builder = cbf.create(entityManager, CallRecords.class)
.where("callerNumber").eq("123456789");
List<CallRecordsDto> result = evm.applySetting(
builder,
EntityViewSetting.create(CallRecordsDto.class)
).getResultList();
Note that this will roughly generate the following optimized query
SELECT
c.id,
c.callerNumber,
o.callrecord.id,
o.id,
o.startTime,
op.id,
op.name
FROM CallRecords c
LEFT JOIN c.callRecordOperators o
LEFT JOIN o.operator op
WHERE c.callerNumber = :param_1
I want to execute a query like this:
SELECT Table1.COL1,
Table1.COL2,
(SELECT SUM(Table2.COL3)
FROM Table2
WHERE Table2.UID = Table1.UID) SUMOF
FROM Table1;
How can I do it?
I usually create a Criteria add ProjectionList to it, to fill COL1 and COL2 only.
I have created a DetachedCriteria to calculate the sum...
Now, how to attach this detached criteria to the main one? My intuition says - it's some sort of Projection which needs to be added to the list, but I don't see how. Also, not sure how WHERE Table2.COL4 = Table1.COL5 of detached criteria will work.
Also, I'm sure this query might be written in different way, for example with join statement. It's still interesting if there's a way to run it like this.
DetachedCriteria and main Criteria
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Table2.class, "table2");
detachedCriteria
.setProjection(
Projections.projectionList()
.add(Projections.sum("table2.col3"), "sumCol3")
)
.add(Restrictions.eq("table2.uid", "table1.uid"))
;
Criteria criteria = session.createCriteria(Table1.class, "Table1");
criteria
.setProjection(
Projections.projectionList()
.add(Projections.property("Table1.col1"), "col1")
.add(Projections.property("Table1.col2"), "col2")
)
;
Entities (very short version)
#Entity
#Table(name = "Table1")
public class Table1 {
#Id
#Column(name = "uid")
public String getUid();
#Column(name = "col1")
public String getCol1();
#Column(name = "col2")
public String getCol2();
#Column(name = "col3")
public String getCol3();
#Column(name = "col4")
public String getCol4();
#Column(name = "col5")
public String getCol5();
}
#Entity
#Table(name = "Table2")
public class Table2 {
#Id
#Column(name = "uid")
public String getUid();
#Column(name = "col3")
public BigDecimal getCol3();
#Column(name = "col4")
public String getCol4();
#Column(name = "col5")
public String getCol5();
}
For a correlated subquery (like the one you presented above), you can use #Formula which can take an arbitrary SQL query. Then, you'll need to fetch the entity and the subquery will be executed.
However, a native SQL is more elegant if you only need this query for a single business requirement.
As for derived table queries (e.g. select from select), neither JPA nor Hibernate support derived table queries for a very good reason.
Entity queries (JPQL pr Criteria) are meant to fetch entities that you plan to modify.
For a derived table projection, native SQL is the way to go. Otherwise, why do you think EntityManager offers a createNativeQuery method?
This is my Entity configuration
#Entity
#NamedQuery(name = "Payment.findByEmail", query = "SELECT p FROM Payment p JOIN p.additionalAuthData a " +
"WHERE KEY(a) = 'email' AND VALUE(a) = ?1 AND (p.paymentType = 4 OR p.paymentType = 10)")
public class Payment {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Long id;
#Column(name = "payment_type")
private Integer paymentType;
/** other properties, getters and setters */
#ElementCollection
#CollectionTable(name = "additional_auth_data")
#MapKeyJoinColumn(name = "id", referencedColumnName = "id")
#MapKeyColumn(name = "field")
#Column(name = "data_value")
private Map<String, String> additionalAuthData;
}
The NamedQuery findByEmail("test#example.com") generates the following SQL
select -- all fields ...
from payment payment0_ inner join additional_auth_data additional1_ on payment0_.id=additional1_.id
where
additional1_.field='email' and (select additional1_.data_value from additional_auth_data additional1_ where payment0_.id=additional1_.id)='test#example.com' and (payment0_.payment_type=4 or payment0_.payment_type=10)
which is wrong: it may work if you have only one row but it blows up otherwise. H2 complains Scalar subquery contains more than one row and PostgreSQL more than one row returned by a subquery used as an expression. In fact, query's where condition compares a scalar value ('test#example.com') with a subquery.
The correct SQL should be:
select -- all fields
from payment payment0_ inner join additional_auth_data additional1_ on payment0_.id=additional1_.id
where additional1_.field='payerEmail' and additional1_.data_value='test#example.com' and (payment0_.payment_type=4 or payment0_.payment_type=10)
Is the HSQL correct? Is there a way to instruct Hibernate to generates a clever, better SQL? Is this a Hibernate bug?
Note: Hibernate shipped with Spring Boot Starter 1.3.7.RELEASE
Edit:
Using an #Embeddable class
#ElementCollection
#JoinTable(name = "additional_auth_data", joinColumns = #JoinColumn(name = "id"))
#MapKeyColumn(name = "field")
#Column(name = "data_value")
private Set<AdditionalData> additionalAuthData;
#Embeddable
public static class AdditionalData {
#Column(name = "field", nullable = false)
private String field;
#Column(name = "data_value")
private String dataValue;
protected AdditionalData() {
}
public AdditionalData(String field, String dataValue) {
this.field = field;
this.dataValue = dataValue;
}
/** Getters, setters; equals and hashCode on "field" */
}
#NamedQuery(name = "Payment.findByEmail", query = "SELECT p FROM Payment p JOIN p.additionalAuthData a " +
"WHERE a.field = 'email' AND a.dataValue = ?1 AND (p.paymentType = 4 OR p.paymentType = 10)")
solves the problem, and the SQL is correct, but it looks just plain wrong, like shooting a fly with a bazooka...
It generates correct SQL without value().
Use just a=?1
But I would expect is should generate it simple also with it.
I am using JPA and Spring for my db tasks and I need to have a join query like below in the JPA Repo class
#Query("SELECT 1 as id, COUNT(bill) as bills, ba.resource, MAX(b.updatedAt) as latestdate FROM Bill b join b.billComp ba where ba.comp.comp = ?1 group by ba.resource")
public List<BillCalc> findByBills(Long comp);
My Entity class is as below
#Entity
public class BillCalc {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(name = "latestdate", nullable = false)
private Date latestdate;
#Column(name = "bills", nullable = false)
private Long bills;
#Column(name = "resource", nullable = false)
private String resource;
I cannot create a table for this and can someone help me in getting the mapping to work? It gives me an error saying cannot cast from Object to BillCalc.
I tried #SubSelect but it does not take parameters
add a constructor to BillCalc.
BillCalc(Integer id, long bills, String resouce, Date latestdate) {...}
then use a Select new query:
SELECT new BillCalc(1, COUNT(bill), ba.resource, MAX(b.updatedAt))
FROM Bill b join b.billComp ba
WHERE ba.comp.comp = ?1 group by ba.resource")
#See Chapter 4.8.2 "Constructor Expressions in the SELECT Clause" in JSR-000220 Enterprise JavaBeans 3.0 Final Release (persistence)