CODEWITHSUNDEEP
javahibernatehql
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Reputation: 75

Hibernate get() method vs hql. which would be best approach?

I am trying to understand the best solution for the following use case. Any inputs would be really helpful.

Consider the following scenario: A,B,C,D are four tables, with One to many mapping between them.

A --> B --> C --> D
A (One) --> B (Many) and so on..

My use case is, I need to get the data from table A based on a column value in D which is not a primary key.

As per my understanding (Still new to Hibernate, so please correct me if i am wrong :)), there are 2 approach

Approach 1: Using the get() method First get the primary key value using the hibernate Query and then call the get method

Query query = sessionFactory.getCurrentSession().createQuery("from D where ...");

Int id = query.list().get(0).getId();
this.sessionFactory.getCurrentSession().get(id);

Approach 2: Use hibernate query and joins Create a string by joining all the 4 tables and pass to the create query method.

Query query = sessionFactory.getCurrentSession().createQuery(sql);

I want to know:

  1. Is there a way to call get method by passing non primary key column value
  2. apart from these approach is there any other approach?
  3. which is better approach

Thanks in advance.

Upvotes: 0

Views: 810

Answers (1)

JB Nizet
JB Nizet

Reputation: 691765

Using a dedicated query returning the wanted data directly will of course be more efficient that executing a query to find D, and then getting C from D, B from C and finally A from B. Especially if the associations are lazy.

Efficiency is not the only thing that matters, though. But since you need to write a query to get D anyway, I would write the query to get the wanted information instead.

Just a note on your first strategy:

int id = query.list().get(0).getId();
D d = (D) this.sessionFactory.getCurrentSession().get(id);

The second line is completely useless. It will return the entity that was already found by the query. All you need is

D d = (D) query.list().get(0);

or better, since the query should return a single entity

D d = (D) query.uniqueResult();

Also, what you pass to createQuery() is not SQL. It's HQL. Those are different languages.

Upvotes: 1

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