如何使用 JPA 执行此 SQL 查询？

Question

Hello everyone I try do this query "SELECT SUM(cevecoin) FROM coin where clid="ABC" in JPA but it's no working. Can somebody help me?

public Integer SumCoin(String Clid) {
    CriteriaBuilder builder =getSession().getCriteriaBuilder();
    CriteriaQuery<CoinBean> criteria =builder.createQuery(CoinBean.class);
    Root<CoinBean> root = criteria.from(CoinBean.class);
    criteria.select(builder.sum(root.<Integer>get("clid")).as(CoinBean.class)).where(builder.equal(root.get("clid"),Clid));
    return getSession().createQuery(criteria).getSingleResult().getCevecoin();
}

Answer 1

try this:

CriteriaBuilder builder =getSession().getCriteriaBuilder();
// the type of query criteria must correspond to the result we want to obtain
CriteriaQuery<BigDecimal> criteria = builder.createQuery(BigDecimal.class);
Root<CoinBean> root = criteria.from(CoinBean.class);
// use multiselect and sum the field cevecoin
criteria.multiselect(builder.sum(root.get("cevecoin")))
criteria.where(builder.equal(root.get("clid"),Clid));

return getSession().createQuery(criteria).getSingleResult();