我按日期进行sql统计。
这意味着按日期划分的访客总数。

select sum(r.count) from (SELECT DATE_FORMAT(reg_date,'%Y-%m-%d') m, COUNT(distinct client_ip) as count FROM request_log GROUP BY m) as r;

以下是此sql的结果[在此处输入图像描述][1]
所以，我想把这个换成 QueryDSL . 我阅读了以下文件并尝试了这些。http://www.querydsl.com/static/querydsl/3.6.3/reference/ko-kr/html_single/#alias

@Transactional
@SpringBootTest
public class QueryDslTest {

    @PersistenceContext
    EntityManager em;

    @Test
    @DisplayName("QueryDSL_TEST")
    public void testQuerydsl() throws Exception {
        JPAQueryFactory queryFactory = new JPAQueryFactory(em);

        QRequestLog requestLog = new QRequestLog("requestLog");

        StringTemplate dateFormat = Expressions.stringTemplate(
                "DATE_FORMAT({0}, {1})"
                , requestLog.regDate
                , ConstantImpl.create("%Y-%m-%d"));

        JPQLQuery<Long> countDistinct = JPAExpressions.select(requestLog.clientIp.countDistinct());

                QueryResults<Tuple> count = queryFactory
                        .select(requestLog.regDate, requestLog.clientIp.countDistinct().as("count"))
                        .from(requestLog)
                        .groupBy(dateFormat, requestLog.regDate)
                        .fetchResults();

//                Long fetch = queryFactory
//                        .select(Projections.fields(Long.class, ExpressionUtils.as(
//                                select(requestLog.regDate, requestLog.clientIp.countDistinct().as("c"))
//                                        .from(requestLog)
//                                        .groupBy(dateFormat, requestLog.regDate), "r")
//                                                  ))
//                        .from(requestLog)
//                        .fetchOne();

//        JPAQuery<Tuple> tupleJPAQuery = queryFactory
//                .select(dateFormat, countDistinct)
//                .from(requestLog)
//                .groupBy(dateFormat);
//
//        queryFactory
//                .select(tupleJPAQuery)

        System.out.println("count = " + count);

//                queryFactory
//                        .select(requestLog)
//                        .from(
//                                select(requestLog.regDate.as("d"), requestLog.clientIp.countDistinct().as("c"))
//                                .from(requestLog)
//                                .groupBy(requestLog.as("d"))
//                             )
    }

}```

I don't know how to use an subquery alias. 

Can you give me a hint?

  [1]: https://i.stack.imgur.com/WUMkl.jpg