How to use CriteriaQuery SUM of custom operation on some cells?

Question

Consider you have table T, with fields A and B.

With regular SQL, I could do this:

SELECT SUM(A * (100.0 - B) / 100.0) AS D FROM T;

Answer 1

The CriteriaBuilder interface provides the following arithmetic functions:

• addition: sum(a, b)
• substraction: diff(a, b)
• multiplication: prod(a, b)
• division: quot(a, b)

where a b parameters can be an expression and/or literal.

As for the query, here is an exampe written in a human readable form:

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery q = cb.createQuery(Number.class);
Root t = q.from(T.class);

// build SUM(A * (100.0 - B) / 100.0) expression
Expression diff = cb.diff(100.0, t.get("B"));
Expression prod = cb.prod(t.get("A"), diff);
Expression quot = cb.quot(prod, 100.0);
Expression sum = cb.sum(quot);
q.select(sum.alias("D"));

System.out.println(em.createQuery(q).getSingleResult());

You can also build the query as an one-liner:

q.select(cb.sum(cb.quot(cb.prod(t.get("A"), cb.diff(100.0, t.get("B"))), 100.0)).alias("D"));

I hope it clarifies your doubts.