hibernate SQLquery extract variable

Question

How can I extract variables total, min, max from hibernate SQL queries and assign them to java variables?

(select count(*) as total, min(price) as min, max(price) as max from product).addScalar("total", Hibernate.INTEGER).addScalar("min", Hibernate.INTEGER).addScalar("max", Hibernate.INTEGER);

Answer 1

This post should help you.

Later edit:

String sQuery = "select min(myEntity.x), max(myEntity.y) from MyEntity myEntity";
Query hQuery = session.createQuery(sQuery);
List result = hQuery.list();

Iterator iterator = result.iterator();

while (iterator.hasNext()) {
    Object[] row = (Object[])iterator.next();
    for (int col = 0; col < row.length; col++) {
        System.out.println(col[i]);
    }
}

Answer 2

Scalar queries return a List of Object arrays (Object[]) - or a single Object[] in your case.

It is however possible to return non-managed entities using a ResultTransformer. Quoting the Hibernate 3.2: Transformers for HQL and SQL blog post:

SQL Transformers

With native sql returning non-entity beans or Map's is often more useful instead of basic Object[]. With result transformers that is now possible.

List resultWithAliasedBean = s.createSQLQuery(
  "SELECT st.name as studentName, co.description as courseDescription " +
  "FROM Enrolment e " +
  "INNER JOIN Student st on e.studentId=st.studentId " +
  "INNER JOIN Course co on e.courseCode=co.courseCode")
  .addScalar("studentName")
  .addScalar("courseDescription")
  .setResultTransformer( Transformers.aliasToBean(StudentDTO.class))
  .list();

StudentDTO dto =(StudentDTO) resultWithAliasedBean.get(0);

Tip: the addScalar() calls were required on HSQLDB to make it match a property name since it returns column names in all uppercase (e.g. "STUDENTNAME"). This could also be solved with a custom transformer that search the property names instead of using exact match - maybe we should provide a fuzzyAliasToBean() method ;)

See also

• 16.1.5. Returning non-managed entities