using subqueries in jpa criteria api

Question

I\'m studying JPA criteria api and my database contains Employee table. I am trying to find all the employees who are paid second highest salary. I was able to write JPQL su

Answer 1

As documented, it cannot work because Number is not Comparable:

> Predicate lessThan(Expression x,
                                                               Expression y)

For expression with Number there is method Criteriabuilder.lt that takes such arguments:

c.where(cb.lt(e2.get("salary"), e3.get("salary")));

Other option is to change type argument from Number to something more specific. If salary is Long, following should work:

Subquery sq = c.subquery(Long.class);
Root e2 = sq.from(Employee.class);
sq.select(cb.max(e2. get("salary")));

Subquery sq1 = sq.subquery(Long.class);
Root e3 = sq1.from(Employee.class);
sq1.select(cb.max(e3. get("salary")));

c.where(cb.lessThan(e2.get("salary"), e3.get("salary")));
c.where(cb.equal(e1.get("salary"), sq));