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";
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.
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