NHibernate HQL Query: Expressions in the Select clause

Question

Is there any way to use expressions in the Select clause?

E.g.:

select u.Age/2 from User u

I'm having this exception right now:

NHibernate.QueryException: ',' expected in SELECT before:/ [select u.Age/2 from Business.Entities.User u]

Answer 1

Yes, you can do that. The result of the query will be a List of Object[], where each element of the array is the result of the column calculation. In your example, if the table had 10 rows, then you'd get back a list of 10 items, each with a single-item Object[] containing the age/2 value.

I'd link to the part of the Hibernate docs that describe this behaviour (it has a special name, I can't remember what it is), but hibernate.org seems to be down again.

Answer 2

You just want get the result of u.Age divided by two? You can use HQL but I find it's easier to change the formula attribute in the mapping file.

ie:

<property name="HalfAge" formula="Age / 2" />