I have this SQL query:
select ts.scorename from content_package cp
join content_package_content_package_components cpcps on cpcps.content_package = cp.id
join content_package_component cpc on cpc.id = cpcps.content_package_components
join tests t on t.id = cpc.assessment
join test_scores ts on ts.tests_id = t.id
where cp.tag = 'C_TS_EN_ABSA_G_'
And want to convert it to JPA, ideally Specifications - is this possible?
you can write this query in JPQL but firs you need to create POJO class of your models. if you are using Intelij idea you can create your models in it by going to persistence section ,right click on your data source and select generate persistence mapping by (hibernate or database schema). after creating models you should change your table names to pojo classes in query and so on ....
Related
I want to write this query using Hibernate Criteria language. I am pretty new to Hibernate and not able to convert this query into Criteria form. I referred lots of answers available on SO but in my case I am using inner join on different columns rather than primary key/ foreign key column. I referred this but still can't make it right.
select TableA.columnA1, TableA.columnA2, TableA.columnA3, TableB.columnB1, TableC.columnC2 from TableA inner join TableB
on
cast(TableA.columnA3 as Integer) = TableB.columnB2
inner join
TableC
on
TableB.columnB3 = TableC.columnC1
To handle the joining logic, you are going to want to use from for each of the tables and include all of your conditions from the on-clauses in the where predicate.
Here is a JPA example that handles a parent-child relationship without having a foreign-key relationship:
EntityManager em = getDb().getEntityManager();
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Child> criteria = cb.createQuery(Child.class);
Root<Parent> p = criteria.from(Parent.class);
Root<Child> c = criteria.from(Child.class);
Predicate condition = cb.and(
cb.equal(c.get(Child_.parentId), p.get(Parent_.id)),
...
);
criteria.where(condition);
criteria.select(c);
criteria.orderBy(cb.asc(c.get(Child_.createDate)));
TypedQuery<Child> q = em.createQuery(criteria).setMaxResults(limit);
A JPA example is provided here, because the Hibernate criteria API is deprecated in favor of the JPA criteria API (see Legacy Hibernate Criteria Queries).
Currently i am using the CreateSQLQuery query model to read the data from database using HIbernate. Now, I want to modify my query by using either HQL or Hibernate Criteria. My query looks like as follows.
select concat(d.AREA,' ',d.CITY) as location, a.TRANSFERRED_DATE as ActualTransferDate, concat(c.SCAN_CODE,',',c.SERIAL_NO) as ScanserialCode, c.MODEL_NO as ModelNum, c.ASSET_NAME as AssetName from table_transfer a, table_category b, table_asset c, table_location d where a.ASSET_ID = c.ASSET_ID and b.ASSET_CATEGORY_ID = c.ASSET_CATEGORY_ID and a.TRANSFER_TO_LOCATION=d.LOCATION_ID"
I am not sure how can i can convert this to Hibernate SQL or Criterion based query. Can any one help me?
You can introduce the fields for location and scanserialCode in your entity and mark them as #Formula
e.g.
#Formula("concat(d.AREA,' ',d.CITY)")
private String location;
See an example here or here
Then use join and where in HQL or Hibernate Criteria
I am trying to build this query with JPA Criteria API
SELECT s FROM snapshot s
INNER JOIN (
SELECT collector_id, entity_id, MAX(timestamp) AS "timestamp"
FROM snapshot GROUP BY collector_id, entity_id
) AS j ON s.TIMESTAMP = j.TIMESTAMP AND s.collector_id = j.collector_id AND s.entity_id = j.entity_id;
The inner select should get 3 properties to identify a snapshot, and then the outer select will get all the other properties of a snapshot based on 3 that inner select returned.
I have success with building the inner select, but how to combine the outer select with the inner using a join?
Or, maybe, there is a different way to construct the query itself in a way, that doesn't include a sub query...
EDIT:
Similar quertion: jpa criteria-api: join with subselect
JPA does not support sub-selects in the FROM clause. Some JPA providers may support this.
For example EclipseLink does:
http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Querying/JPQL#Sub-selects_in_FROM_clause
In Hibernate, I created a query using JOIN to join two tables. The query executes fine in Oracles SQL Developer. However, if I add it to a #NamedQuery, the server starts with this error:
Error in named query: loadFooByAnother: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: ON near line 1, column xxx
My named query is:
SELECT foo FROM FooTable foo JOIN BarTable bar
ON foo.something=bar.somethingId
WHERE bar.anotherId=:another
Is it not possible to use JOIN .. ON syntax in Hibernate?
You need to use the with directive, if you use HQL:
SELECT foo
FROM FooEntity foo
JOIN foo.bar b with b.name = :name
WHERE foo.prop = :prop
This is for supplying a custom ON clause. From your example, judging from how you joined tables, I think you tried to execute a native SQL using a #NamedQuery.
If you want to run a native SQL query, you have to use #NamedNativeQuery instead.
If you want to use HQL, you need to use Entities and to join Entity associations (not tables).
If you use JPQL then the with directive has to be replaced by the on directive, but again, you need to navigate entity associations, meaning you have to map them first.
I have a query like below
select f.id, s.name, ss.name
from first f
left join second s on f.id = s.id
left join second ss on f.sId = ss.id
If I could use HQL, I would have used HQL constructor syntax to directly populate DTO with the result set.
But, since hibernate doesn't allow left join without having an association in place I have to use the Native SQL Query.
Currently I am looping through the result set in JDBC style and populating DTO objects.
Is there any simpler way to achieve it?
You could maybe use a result transformer. Quoting Hibernate 3.2: Transformers for HQL and SQL:
SQL Transformers
With native sql returning non-entity
beans or Map's is often more useful
instead of basic Object[]. With
result transformers that is now
possible.
List resultWithAliasedBean = s.createSQLQuery(
"SELECT st.name as studentName, co.description as courseDescription " +
"FROM Enrolment e " +
"INNER JOIN Student st on e.studentId=st.studentId " +
"INNER JOIN Course co on e.courseCode=co.courseCode")
.addScalar("studentName")
.addScalar("courseDescription")
.setResultTransformer( Transformers.aliasToBean(StudentDTO.class))
.list();
StudentDTO dto =(StudentDTO) resultWithAliasedBean.get(0);
Tip: the addScalar() calls were
required on HSQLDB to make it match a
property name since it returns column
names in all uppercase (e.g.
"STUDENTNAME"). This could also be
solved with a custom transformer that
search the property names instead of
using exact match - maybe we should
provide a fuzzyAliasToBean() method ;)
References
Hibernate Reference Guide
16.1.5. Returning non-managed entities
Hibernate's Blog
Hibernate 3.2: Transformers for HQL and SQL