JPA计数查询，结果最大

Question

您可以分享我的代码段，以通过JPA编写以生成以下SQL查询

SELECT COUNT(*) FROM Customer c 
WHERE c.countryId ='Canada' AND 
      c.lanuguage ='ENG' AND 
      ROW_NUM <=10;

因为我尝试了以下方式。但是MaxResults没有应用，这似乎我能够收到超过10的计数。

Query query = em.createQuery("SELECT COUNT(c) FROM Customer c where c.countryId ='Canada' and c.lanuguage ='ENG'");
query.setMaxResults(10);
long customerCount = (Long)query.getSingleResult();

Answer 1

选择"计数"将始终返回一个值。如果您想低于10的计数，请添加。

SELECT COUNT(c) AS 
FROM Customer c
WHERE c.countryId='Canada' and c.language='END'
HAVING COUNT(c)<=10