如何使用JPA和Criteria API对不区分大小写的列进行Distinct计数

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;

public class JpaDistinctCountExample {
    public static void main(String[] args) {
        // 创建EntityManagerFactory
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("your-persistence-unit-name");
        
        // 创建EntityManager
        EntityManager em = emf.createEntityManager();
        
        // 获取CriteriaBuilder对象
        CriteriaBuilder cb = em.getCriteriaBuilder();
        
        // 创建CriteriaQuery对象
        CriteriaQuery<Long> cq = cb.createQuery(Long.class);
        
        // 设置查询的根实体类
        Root<YourEntity> root = cq.from(YourEntity.class);
        
        // 设置查询的列和去重
        cq.select(cb.countDistinct(root.get("columnName")));
        
        // 添加查询条件，不区分大小写
        cq.where(cb.equal(cb.lower(root.get("columnName")), "your-value".toLowerCase()));
        
        // 创建TypedQuery对象
        TypedQuery<Long> query = em.createQuery(cq);
        
        // 执行查询并获取结果
        Long count = query.getSingleResult();
        
        // 输出结果
        System.out.println("Distinct Count: " + count);
        
        // 关闭EntityManager和EntityManagerFactory
        em.close();
        emf.close();
    }
}