Left join in two tables unrelated with JPQL

Question

I have a problem with creating a query in JPQL to join two tables Table1 and Table2 by a field called code (make LEFT JOIN ).

The problem is that my two entities don't have the relations with JPA (and I need to do it that way).

I searched for a solution but I have not found it yet.

Answer 1

You can have the entity manager perform a native query. See this page section "Utilizing Native SQL Queries"

So your code would look like this:

List<SOME_DATA_TYPE> list = (List<SOME_DATA_TYPE>)em.createNativeQuery
  ("SELECT * FROM table1 a join talbl2 b on a.somefiedd = b.somefield " ,    some.package.name.SOME_DATA_TYPE.class)
                              .getResultList(); 

Technically not JPQL but still JPA. It's an idea. Hope that helps.

Answer 2

如果您没有使用正确的实体关系，则不能使用JPQL，但您可以使用本机查询，考虑使用它们来解决您的需求。