using multiple table in hibernate, problem with output

Question

I am using following query

from A as a,B as b,C as c where a.val='1' and b.val=a.val and c.val=b.val

Now if i do follow

query.list();

what will be the output?

Also if I want to get the output of above query what else I have to do?

Answer 1

Hi this is not the right way.For this you have to write nested query Using Criteria.That will be something like as follows:

 String query="from A a where a.val in (select b.val from B b where b.val in (select c.val from C c where c.val='1'))";    
 Criteria criteria = session.getSession().createCriteria(TableName.class);
        criteria.add(Restrictions.sqlRestriction(query));
   List<tableNameObj> tableNameObj=criteria.list();

Hopefully this will solve your problem.

Answer 2

From the Hibernate Reference Documentation:

14.2. The from clause

...

Multiple classes can appear, resulting in a cartesian product or "cross" join.

from Formula, Parameter

from Formula as form, Parameter as param

So your query will return a cartesian product and if there are X matching rows in A, Y matching rows in B, Z matching rows in C, you'll get X * Y * Z results (and the product can become huge very quickly).

Be very careful with this kind of queries, they are very greedy with resources and might cause serious performance problems.