Question

I am porting an application for KodoJDO to Hibernate.
I have a query that goes across 4 tables in the db, and 3 objects in the java code.

In English the query is Find the users that have entitlements in system X.

my JDOQL where clause called on the User object was
where entitlements.contains(ent) && (upper( ent.system.id ) = ‘EVPN’)

some sql that does the query is:

 select unique(u.id)
 from USER u, USERENTITLEMENT ue, ENTITLEMENT e, SYSTEM s
 where u.id = ue.userid
 and ue.entitlementid = e.id
 and e.systemid = s.id
 and s.id = 'evpn'

My best guess for HQL gives me an exception

org.hibernate.hql.ast.QuerySyntaxException: unexpected AST node: ( [select user from com.ebig.entity.User as user, com.ebig.entity.Entitlement as ent, com.ebig.entity.System as sys where  entitlements.contains(ent) and ent.system = sys and sys.id  = 'evpn']

the db is structured like this:

 User
   id

 UserEntitlement
   userid
   entitlementid

 Entitlement
   id
   systemid

 System
   id

the java code is structured as below:

 class User 
 {
    String id;
    Set<Entitlement> entitlements;
 }

 class Entitlement
 {
    String id;
    System system;
 }

 class System
 {
    String id;
 }

Update My final query that works

            hqlQuery = "select distinct user from User as user "+
        "inner join user.entitlements as entitlement inner join entitlement.system as system "+
        "where  system.id  = 'evpn'  AND mod(user.flags, 2) = 0  AND source = 1";

Yes I know I should use parameters, but I have a great many problems to solve, and will post pone that code for another day.

Another variation with an implicit inner join for entitlement to system

        hqlQuery = "select distinct user from User as user "+
        "inner join user.entitlements as entitlement "+
        "where  entitlement.system.id  = 'evpn'  AND mod(user.flags, 2) = 0  AND source = 1";

Answer 1

You should use joins :

select distinct u.id from User u
inner join u.entitlements as entitlement
inner join entitlement.system as system
where system.id = :evpn

where :evpn is a named parameter that you have to bind.

You must think in terms of objects and relationships between objects when doing HQL, and not in terms of tables, foreign keys and join tables.