Question

我有以下查询

select sum(r.score)/count(r) from Rating as r
    group by r.item
    order by sum(r.score)/count(r) desc

我的问题是hibernate舍入结果总和（r.score）/ count（r）。

如何强制Hibernate返回结果的浮点值？

Answer 1

如果您只想找到一个平均值，那么您可以使用avg()聚合函数，该函数始终返回Double。

select avg(r.score) from Rating as r
    group by r.item
    order by avg(r.score) desc

Answer 2

avg最适合这种情况。对于要转换为double的一般情况，您可以使用CAST：

select sum(r.score) / (CAST (count(r) AS DOUBLE PRECISION)) from Rating as r
    group by r.item
    order by sum(r.score) / (CAST (count(r) AS DOUBLE PRECISION)) desc

如何在Hibernate Query的ResultSet中获取浮点值？

2 个答案: