HQL Query to check if size of collection is 0 or empty

Question

I try to generate a HQL query that include user with a empty appoinment collections(mapped by OneToMany):

SELECT u FROM User u JOIN u.appointments uas WHERE          


        

Answer 1

// Hibernate query:
const string hql = "from User u where u.Id = 101 and size(u.Appointments) = 0";

Answer 2

Have you taken a look at your generated SQL? Your method works fine here:

// Hibernate query:
const string hql = "from User u where u.Id = 101 and size(u.Appointments) = 0";


// Generates this working SQL:
select user0_.Id    as Id20_,
       user0_.Name as Name2_20_
from   User user0_
where  user0_.Id = 101
       and (select count(appointment1_.Id_Solicitud)
            from   Appointment appointment1_
            where  user0_.Id = appointment1_.Id_User) = 0

Answer 3

Using IS EMPTY should work (I would favor a JPQL syntax):

SELECT u FROM User u WHERE u.status = 1 AND u.appointments IS EMPTY

If it doesn't, please show the generated SQL.

References

• Hibernate Core Reference Guide
  • 14.10. Expressions
• JPA 1.0 specification
  • Section 4.6.11 "Empty Collection Comparison Expressions"