Question

I think this is nearly impossible or very tricky. I’m using CriteriaBuilder, JPA 2.0, Hibernate and MariaDB and want to build the following query with CriteriaBuilder:

SELECT COUNT(*) FROM
   (SELECT DISTINCT(SomeColumn) // I think this is not possible?
    FROM MyTable
    WHERE ... COMPLEX CLAUSE ...
    GROUP BY SomeColumn) MyTable

My Question: Possible? And if, how?

Thanks for wrapping your mind around this!

Mark

Answer 1

This example assumes that you’re using Metamodel generation.

CriteriaQuery<Long> cq = cb.createQuery(Long.class);
Subquery<SomeColumnType> subcq = cq.subquery(SomeColumnType.class);
Root<MyTable> from = subcq.from(MyTable.class);
subcq.select(from.get(MyTable_.someColumn));
subcq.where(** complex where statements **);
subcq.groupBy(from.get(MyTable_.someColumn));
cq.select(cb.count(subcq));