JPA-如何实现此SQL行为（左联接父实体到先前内部联接的子实体和大子实体）

Question

I'm not being able to find out the way to achieve desired result with JPA/JPQL as I'm with this SQL query:

select parent.id, child.id, grandchild.id
from salesforce.parent__c parent 
left outer join salesforce.child__c child  
inner join salesforce.grandchild grandchild on child.grandchild_id__c=grandchild.sfid 
and (grandchild.token__c='....') 
on parent.sfid=child.parent_id__c
where (parent.external_id__c is not null) 
and parent.displayed__c=true 
and parent.internal__c=false 
and parent.date__c>='....' 
and parent.date__c<='....' 
order by parent.date__c asc

The target output of the query I'm looking for would be something like this:

Parent  Child   Grandchild
P1  null    null
P2  null    null
P3  C1  GC1
P4  C2  GC2

Where all records from parent meet parent's filters, and a child record is not returned unless its grandchild meets gc's filters.

My best guess on JPQL would be something like this

SELECT DISTINCT p FROM Parent p 
LEFT JOIN p.childs cl 
INNER JOIN cl.grandchilds c 
ON c.token__c = '....' 
ON cl.parent__c = p.sfid 
WHERE p.external_id__c IS NOT NULL 
AND p.displayed__c = true 
AND p.internal__c = false 
AND p.date__c >= '....' 
AND p.date__c <= '....' 
ORDER BY p.date__c asc

But this is throwing org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: ON

The way i'm doing the query i assume is just OK:

String queryTxt = "SELECT DISTINCT p FROM Parent p LEFT JOIN p.childs cl INNER JOIN cl.grandchilds c ON c.token__c = '....' ON cl.parent__c = p.sfid WHERE p.external_id__c IS NOT NULL AND p.displayed__c = true AND p.internal__c = false AND p.date__c >= '....' AND p.date__c <= '....' ORDER BY p.date__c asc";
TypedQuery<Parent> typedQuery = entityManager.createQuery(queryTxt, Parent.class);
List<Parent> resultList = typedQuery.getResultList();

If I try with the following JPQL it executes fine:

SELECT DISTINCT p FROM Parent p 
LEFT JOIN p.childs cl 
INNER JOIN cl.grandchilds c 
ON c.token__c = '....' 
WHERE p.external_id__c IS NOT NULL 
AND p.displayed__c = true 
AND p.internal__c = false 
AND p.date__c >= '....' 
AND p.date__c <= '....' 
ORDER BY p.date__c asc

But the results are not what i'm looking for, as the inner join between child and grandchild is filtering out as well parent records:

Parent  Child   Grandchild
P3    C1    GC1
P4    C2    GC2

I've also tried with Query query = entityManager.createNativeQuery(strQuery, Parent.class); using the SQL query on the beginning of the post, replacing the select part with parent. , child. , grandchild.*, but then I'm not being able to parse full structure properly either :-\\

Answer 1

You can do any query with FluentJPA and use its Tuple support for projections. Provide me your entities and I will draft you the full solution.