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Querying/Selecting rows from Parent Entity when using Hibernate JOINED inheritence strategy

I know there are three types of inheritence strategies: SINGLE_TABLE, TABLE_PER_CLASS, JOINED. I think the best choice is JOINED if I want my underlying database to be normalized. However, let us consider this usecase: I have a Parent Entity and one Child Entity that extends this Parent Entity. The inheritence strategy I am using is JOINED. Now, from the front-end of the application I can add Parent and Child entities. When I do search from front-end to get all Child Entities I am able to get all the Child Entities. Now, when I try to do a search only on Parent Entity I see that the result set contains all the entities(Parent + Child) and I understand why this is happening. My question is that is there any way we can search/query for only Parent entities(excluding rows from Child entity) when I am using the JOINED inheritence startegy?

Newer versions of Hibernate optimize this, but you have to make sure you are not selecting the entity or use fields of the parent table.

save parent in hibernate with child

I am lil bit confused in hibernate,
Here i am having one parent object and this parent object (Suppose A is a parent and B is child object) has many to one unidirectional relation with child object B.
Now, I have a object A along with Object B . What i have done is , i saved all the child objects in database, so now every child objects are saved in db and have id .
Now i want to save parent object A for its related child object. How can i do that ?
Though it might be very simple for u guys, i am new to hibernate. so need lil help.
Thanx in advance. :)

Why are you saving parent and child separately? Set the child to parent and merge the parent. Underlying ORM technology will take care of rest. But just add cascade type PERSIST and MERGE (ideally PERSIST is enough, but MERGE handles updates as well) over the relationship in parent entity.

Hibernate - Updating an ID of a parent in a child without updating parent?

I couldn't find the answer or didn't phrase this question properly. If you guys know... let me know :-)
I have a parent which has children....
on the child, I have regular vars that map to column names
However, one is mapped as many-to-one. The child basically contains the ID for the parent. Except in the child I obviously contain the entity of the parent, not the id.
ie: (QUICK simple example....)
#ManyToOne(fetch= FetchType.EAGER)
#JoinColumn(name="bcId",referencedColumnName="id")
private ParentEntityClass theParentClass;
How, can I set the the parent object in this hibernate entity so it ONLY uses the parent entity for the ID and doesn't try to save the parent. Should I use Cascade.refresh so it refreshes but doesn't update the parent?
Thanks :)

Disable update to many to one entity in hibernate

I have a Parent and Child entity. Child has a Manytoone annotation to reference Parent. The use case is that when i load a child by findById and get the parent out using the getter. then If I update the parent, I am able to save the parent. I do not want the parent to be updatable which is pulled out from a child.
I want only to update parent if I directly find it by id and change attribute and save.
I know hibernate has no info when i do getParent() from child that it got it from child and not find by id and makes an update to parent.
I tried Immutable annotation on ManytoOne on Parent but it does not prevent an update to be fired.
Is there any way that I can make the parent pulled out from a child non-updatable?
feel free to ask any clarifications.

The problem you are experiencing, in fact belongs to the Hibernate Session. It has nothing with Cascading. Because the session is designed to be a unit-of-work for us.
Whenever you access an object 1) by ID or 2) by reference, this object is (from that moment) "cached" in the Session. It is one instance shared accross all the handling during the Session life-time.
So, once, the Parent is loaded into session, and you are amending it anyhow, and later Session is flushed - any changes to Parent are persisted.
You can call session.evict(parent) explicitly, to avoid changes propagation during the Flush.
But It seems to me a bit weird, that you are changing the Parent (accidently...maybe) while working with child and not willing to store these changes. Other words, maybe solution is to change the approach.

You can call EntityManager.detach() on the parent that you obtain through the getter. Any change made to the detached entity will not be synchronized to the database.

JPA cannot delete entities with a onotomany relation and a cascatype all

I am trying to delete an entity but when I use the entity manager i do not have errors but te data is still in the database, I am using cascade all, independently of this, I am deleting its parent reference as
Parent parent = child.getParent();
parent.getChildren().remove(child);
entityManager.remove(child);
entityManager.merge(parent);
Does anyone know a way to do this?

This can have several reasons:
You are not removing the parent reference from the child - child.setParent(null);
This is important since the parent id is probably stored inside the child table.
The removal is not committed yet when you are calling merge. This should not be an issue, but if the first idea does not help I would try and put the deletion and the merge in separate transactions.
I assume that you are using CascadeType.ALL on the parent only.

Edit according to Chris comment because it was indeed not clear at all.
1st, you have to understand than an entity instance can have many states. http://openjpa.apache.org/builds/1.2.3/apache-openjpa/docs/jpa_overview_em_lifecycle.html
Merge is here to attach an entity to the current entityManager. Once it's managed, all modification you will make on the entity will be persisted in database when the EntityManager is flushed. This happen normally at the end of the current transaction (or when you call flush manually or when the entityManager estimates that it's necessary).
If your entities have been retrieved from the DB inside the current transaction, you don't need to call merge as they already are managed.
Assuming this
You just need to call
entityManager.remove(child);
Or
parent.getChildren().remove(child);
if you've configured orphan removal on the relationship (in parent).
This will so be automatically flused to the database when the current transaction will be flushed and NOT at the method call.
Otherwise you can force flushing by using entityManager.flush()but it's a bad practice. Anyway you won't see the change in the database until the transaction is commited / closed.
If you want to remove a child using entityManager.remove(child) you must ensure to apply associated modification on parent entity (using parent.getChildren().remove(child) and not entityManager.refresh(parent)) if your parent instance is currently managed (means it actually exists an instance of your parent in memory, because you've retrieved it or because you've called child.getParent() or because it was eagerly loaded when you retrieved the child.)