Hibernate Criteria限制与投影alise

Question

I am using hibernate version 3.6.10.Final and hibernate-jmx.version 3.5.6-Final.. I have a Hibernate Criteria

getCurrentSession().createCriteria(CustOrder.class)
        .createAlias("custOrderSubStatusComments", "comment")
        .setProjection(Projections.projectionList()
                .add(Projections.groupProperty("id"))
                .add(Projections.max("comment.id"))
                .add(Projections.property("comment.value"), "val")
        )
        .add(Restrictions.eq("val", haltreason)).list();

This code is giving error org.hibernate.QueryException: could not resolve property: val of: com.**.CustOrder

But the following code is working fine.

getCurrentSession().createCriteria(CustOrder.class)
        .createAlias("custOrderSubStatusComments", "comment")
        .setProjection(Projections.projectionList()
                .add(Projections.groupProperty("id"))
                .add(Projections.max("comment.id"))
                .add(Projections.property("comment.value"), "val")
        )
        .addOrder(Order.asc("val")).list();

I don't understand why "val" is valid with ordering and invalid with restrictions.

Answer 1

Same with "normal" SQL.

The select clause is what you present as the query results. For example I cannot do the following...

select first_name f 
from customer
where f='hello';

But I can do...

select first_name f 
from customer
where first_name='hello'
order by f;

If you could, you would be able to write expressions that don't make much sense, for example...

select age + 10 as AgePlusTen
from Person
where AgePlusTen < 70;

If you really wanted to, you could use a sub-select...

select * from (
    select age + 10 as AgePlusTen
    from Person
) where AgePlusTen < 70;