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Converting SQL query with joins to JPA

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 ....

Spring data jpa from multiple tables

I am using spring data jpa. And I have a inner join on two tables. This is my query.
SELECT A.NAME, A.CARD_NUMBER, A.ADDRESS, A.EMAIL FROM USER_INFO ABC INNER JOIN USR_DETAIL DEF ON (ABC.ID = DEF.ID) WHERE ABC.ID = '123456';
The two table here have no relationship. So one-to-one or many-to-one or many-to-many on the column name doesn't make sense. Can I define entities without relationship? The reason why we are doing a inner join on the two tables here is simply because doing a join on both of them will be a expensive query.

You can define both entities without any kind of relationship and then you can retrieve the data specifying nativeQuery=true in the #Query(..) annotation in the read method.
#Query(value = "SELECT ABC.NAME, ABC.CARD_NUMBER, ABC.ADDRESS, ABC.EMAIL " +
"FROM USER_INFO ABC " +
"INNER JOIN USR_DETAIL DEF ON (ABC.ID = DEF.ID) " +
"WHERE ABC.ID = :id", nativeQuery = true)
UserInfoDetails retrieveUserInfoAndDetailById(#Param("id") String id);
Side notes:
In the projection of the query, I correct the alias from A to ABC as the query was not written correctly. Feel free to edit the projection accordingly to your needs.
As a return type, I wrote a UserInfoDetails class, supposing it will be return something similar. Feel free to change it accordingly to your needs.

Using Spring Data JPA, how can I create a query with multiple conditions ORed on same field?

I need help creating a JPQL query out of a native query having or condition along with other fields. Please lemme know if it is still not supported by JPA.
Sample Native Query :
select * from EMP where (EMP_FLAG is NULL or EMP_FLAG is 'Y') and EMP_ID in (1,2,3);
Now to use JPQL (Java Persistent Query Language) I have written following in-build query using source
findByEmpIdInAndEmpFlagIsNotNull(List<Long> ids);
But how to incorporate the check for EMP_FLAG = 'Y'?
Note** I do not intend to add a query using #Query annotation. (aware
of that solution)
Spring version : 4.2,
JAVA : 1.7

You can do like this
#Query("select e from EMP e where (e.empFlag is null of e.empFlag ='Y')and in :ids")
findByEmpIdIn(#Param("ids") List<Long> ids);

Choose the name you find the best for your method, and annotate it with
#Query("select e from Employee e where (e.empFlag is null of e.empFlag = 'Y') and e.empId in ?1")

JPA Query annotation and joining table

I have a sql query like this
Select * from DB1.Table1 a left join DB2.Table2 b on a.dCode = b.dCode where bID = 123;
How can I create jpa code for the above query? what would be the params of JpaRepository
public interface TestRepository extends JpaRepository<???, ???> {
#Query("???")
??? myTestQueryCOde(Integer bID);
}
What would be at ???

I am not sure if Spring JPA Data support cross DB queries, but have a look at Cross database joins in JPA

getting result set into DTO with native SQL Query in Hibernate

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