How to set DB2 global variable on session from spring data jpa context - jpa

Question

I have a spring data jpa repository. I want to query a database view.
The database is DB2 and supports a feature called 'global variable' which actually is a session variable. The db view declaration uses a global variable.
How do I set the value of this variable at runtime before the view is executed?
Would something like this work?
public interface DomainRepository extends org.springframework.data.jpa.repository.JpaRepository<Domain, IdType> {
#Query(value = "SET SCHEMA.VAR_GLOBAL = :param; SELECT * FROM SCHEMA.DOMAIN", nativeQuery = true)
List<Domain> findByDomain(#Param("param") String param);
}
Are there any alternative solutions?

Answer 1

That's what I want to achieve in SQL:
SET CURRENT APPLICATION COMPATIBILITY = 'V11R1';
SET SCHEMA.VAR_GL = 'Value';
SELECT * FROM SCHEMA.VIEW;
The SCHEMA.VIEW is declared as:
SELECT * FROM SCHEMA.TABLE WHERE field = VAR_GL
I have to mark the public method on the controller with #Transactional annotation to execute the queries together in one db session.
public interface Controller {
#Transactional
List<Options> loadOptions();
}
public class ControllerImpl implements Controller {
#Autowired
private DomainRepository repo;
#Override
public List<Option> loadOptions() {
this.repo.setCompatibilityMode();
this.repo.setGlobalVariableA("Value");
List<Option> list = this.repo.loadDropdown();
return list;
}
In my jpa repository I need a method for each global variable:
public interface DomainRepository extends JpaCrudRepository<Option, OptionPK> {
#Modifying
#Query(value = "SET CURRENT APPLICATION COMPATIBILITY = 'V11R1'", nativeQuery = true)
void setCompatibilityMode();
}
#Modifying
#Query(value = "set SCHEMA.VAR_GL = :value", nativeQuery = true)
void setGlobalVariableA(#Param("value") String value);
#Query(value = "SELECT * FROM SCHEMA.VIEW", nativeQuery = true)
List<Option> loadDropdown();
}
That's how it works. I'd like to improve this solution further but I have no idea how to make the variable query more reusable by making the variable name a parameter.

Answer 2

Variable declarations don't work over JDBC but temp tables do:
DECLARE GLOBAL TEMPORARY TABLE SESSION.myvars
(
VAR_GLOBAL VARCHAR(255)
) ON COMMIT PRESERVE ROWS;

Answer 3

You cannot lump two statements together like in your example, but you should be able to create two different Querys and execute them in separate calls to executeUpdate() and getResultList() respectively. (I'm not very familiar with JPA, I may have used wrong method names, hopefully you get the idea.)

Answer 4

You can try CRUD methods:
public interface DomainRepository extends CrudRepository<Domain, Long>{
List<Domain> findAll();
}