When generating a query on a joined-subclass or table-per-class hierarchy (involving a select-union on the concrete tables), Hibernate does not inject the alias before the "clazz_" condition in the WHERE block.

Consider the class ClassOfInterest with members:

long Id;
OtherClassIface otherEntity;

There is also the superclass type OtherClassIface and the subclasses OtherClassA and OtherClassB. If we run the following query:

from ClassOfInterest c
left join c.otherEntity myAlias1
left join c.otherEntity myAlias2
where myAlias1.class = OtherClassA
and myAlias2.class = OtherClassB
and (myAlias1.fieldA = '123' or myAlias2.fieldB = '456')

The following SQL is generated:

select
classofint0_.id as id1_0_0_,
otherclass1_.id as id1_3_1_,
otherclass2_.id as id1_3_2_,
classofint0_.otherEntity_id as otherEnt2_0_0_,
otherclass1_.fieldA as fieldA1_1_1_,
otherclass1_.fieldB as fieldB1_2_1_,
otherclass1_.clazz_ as clazz_1_,
otherclass2_.fieldA as fieldA1_1_2_,
otherclass2_.fieldB as fieldB1_2_2_,
otherclass2_.clazz_ as clazz_2_
from
ClassOfInterest classofint0_
left outer join
(
select
id,
fieldA,
null as fieldB,
1 as clazz_
from
OtherClassA
union
all select
id,
null as fieldA,
fieldB,
2 as clazz_
from
OtherClassB
) otherclass1_
on classofint0_.otherEntity_id=otherclass1_.id
left outer join
(
select
id,
fieldA,
null as fieldB,
1 as clazz_
from
OtherClassA
union
all select
id,
null as fieldA,
fieldB,
2 as clazz_
from
OtherClassB
) otherclass2_
on classofint0_.otherEntity_id=otherclass2_.id
where
clazz_=1
and clazz_=2
and (
otherclass1_.fieldA='123'
or otherclass2_.fieldB='456'
)

This generates a JDBC exception due to the ambiguous column name. Instead, the marked block should be preceded by the alias of the union select:

otherclass1_.clazz_ = 1
and otherclass2_.clazz_ = 2

(i.e. add the parts in bold)

Problem originally noted in Oracle JDBC but also reproduces in SQLite, which is used in attached test-case.