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

Michel picture Michel · Sep 21, 2010 · Viewed 55.1k times · Source

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 u.status = 1 AND (uas.time.end < :date OR size(uas) = 0)

I tries it on several manners (NOT EXIST ELEMENT(), IS NULL) also see: How to check if the collection is empty in NHibernate (HQL)? (This doesn't work for me)

but still not the result I want to see or some error in HQL or SQL SERVER

Note:

the query without the JOIN works:

"FROM User u WHERE u.status = 1 AND size(u.appointments) = 0"

Solved

Another JOIN solved the problem:

SELECT u FROM User u LEFT JOIN u.appointments pas1 LEFT JOIN pas1.slot t WHERE u.status = 1 AND t.end <= :date1 OR t.end IS NULL ORDER BY u.name asc

Answer

Pascal Thivent picture Pascal Thivent · Sep 21, 2010

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
  • JPA 1.0 specification
    • Section 4.6.11 "Empty Collection Comparison Expressions"