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How to select schema at runtime using Hibernate?

I already have an existing code base, where schema(like db_1, db_2..) are created at run time.
We are currently using JdbcTemplate, using that its quite easy to append schema in the native SQL queries some thing like :-
sql = " Select * from "+schema+".user";
jdbcTemplate.query(sql, new UserMapper());
Now I want to know is how to provide schema to hibernate at runtime like I did with the jdbcTemplate?
What connection url should I provide in hibernate.cfg.xml so that it doesn't connects to a single schema rather whole database?
Any suggestions will be helpfull.
P.S: I am new to hibernate (So I might have missed something stupid)

I know of two options:
Use native SQL query binding results to JPA entities. Details here.
Use Hibernate multi-tenancy. Details here and here.
Although I haven't tried either.

Query with dynamic schema without using string concatenation

I have a system that uses a Oracle database, with a schema that is different from the application user. The schema name itself is not known in advance, so we can't just hardcode it. It's a system property.
Most of the data access is through Hibernate, which can specify the default schema on connection so this is not a problem in those cases.
However, there are a few places where plain SQL queries are used (using spring jdbcTemplate). So right now we have something that boils down to:
Map<String,Object> result = jdbcTemplate.queryForMap("SELECT A, B, C FROM "+schema+".TABLE WHERE blablablah");
And this, of course, is an open SQL injection vulnerability. We're planning security audits and this will be flagged for sure.
So the question is: How do I specify the schema on the query, be it with jdbcTemplate, another Sprint data access utility, or even plain jdbc?
Thank you,
JGN

You can use Connection.setSchema to specify the schema for a JDBC connection. This should be done before you create the Statement to execute a SQL command.

Using #Entity Class When Table Doesn't Exist

I have several database tables that my Spring MVC/JPA application refers to using the #Entity and #Table Annotations. I've run into the issue where if my application switches between database connections, some tables that exist on database 1 may not exist in database 2 (as we are following the SDLC cycle and promoting table additions/changes after they get the "OK"), thus resulting in an SQL Exception when the application server starts.
Does spring offer a way to mark specific #Entity Classes as "Optional" or "Transactional" so there are no database Exceptions returned because of nonexistant tables?

In my opinion, there is no option to do that.
You can add automatic update of schema in Hibernate, but you mentioned that you are doing this manually.
Hibernate is validating the schema, when he establishes connection. You use #Entity, so he looks for that table and throws an error if there is no with the name specified.

Hibernate reveng persistence model does not validate

I use Hibernate Reverse Engineering to automatically create classes from a database scheme. DB server is MSSQL 2008. This database is designed by a partner and could potentially change without notice. Thus I'd like to have Hibernate validate the scheme on startup, wich in my opinion should work out of the box. But it doesn't:
org.hibernate.HibernateException: Wrong column type in somedb.dbo.ASVC_S for column SomeCol. Found: decimal, expected: numeric(18,0)
The generated enttity class looks like this:
#Column(name="SomeCol", precision=18)
public BigDecimal getSomeCol() {
return this.someCol;
}
Is my assumption that reveng creates classes that can be validated against the schema wrong? Should I skip validation and hope that during runtime everything's OK? Annotating the classes after generating them or maintaining an entry for each class in my reveng.xml mapping file is not an option - too many classes ;)
hibernate-tools is version 4.0.0-CR1.

Are Hibernate filters only applied after the data has been loaded from db?

I've found some contradicting information on the net. Does anyone know whether Hibernate filters affect the generated sql, or is it just filtering the data as it's read from the database?

Hibernate filters affect the where clause of the generated SQL.
The Introduction to Hibernate Filters is a nice article on filters and provides a demo application allowing to play with them.

If you enable SQL in Hibernate using show_sql"(+"format_sql"),
and execute query with enabled filter, you will see the result.
For example:
select
item0_.ID as ID0_
from
ITEMS item0_
where
item0_.deleted = 'FALSE' <-- here is filtering