쿼리의 각 행에 대해 다른 쿼리의 상위 20 개를 선택하십시오.

Question

나는 뭔가를하려고하는데, 어떻게해야할지 잘 모르겠습니다.

나는 같은 일부 데이터를 가지고 :

나에게 시간과 이름으로 그룹화 수를 반환

WITH a AS (SELECT theid, thename, thetimestamp FROM mytable) 
SELECT thename, TRUNC (thetimestamp, 'HH24'), COUNT (theid) FROM a 
group by thename,trunc(thetimestamp,'HH24') ORDER BY COUNT (theid) desc) 

.

나는 그냥 싶습니다

for each hour, top X counts 

는 것이 가능할까요?

---

나는 종료와 :

SELECT thename, hour, cnt 
FROM 
(SELECT thename, hour, cnt, 
     rank() over (partition by hours order by cnt desc) rnk 
    FROM 
    (SELECT thename, TRUNC (thetimestamp, 'HH24') hour, COUNT (theid) cnt 
    FROM mytable 
    group by thename,trunc(thetimestamp,'HH24') 
) 
) 
WHERE rnk <= :X 

Answer 1

시도 :

SELECT thename, hour, cnt 
FROM 
(SELECT thename, hour, cnt, 
     rank() over (partition by thename order by cnt desc) rnk 
    FROM 
    (SELECT thename, TRUNC (thetimestamp, 'HH24') hour, COUNT (theid) cnt 
    FROM mytable 
    group by thename,trunc(thetimestamp,'HH24') 
) 
) 
WHERE rnk <= :X 

(그래서 난 내에서 그것을 제거 내가 WITH 절의 목적을 보지 못했다).

Answer 2

row_number()를 사용하여 수행 할 수 있지만 다른 하위 쿼리 또는 다른 CTE가 필요합니다.

WITH a AS (
    SELECT thename, TRUNC(thetimestamp, 'HH24') as hour, COUNT(*) cnt 
    FROM mytable 
    GROUP BY thename, TRUNC(thetimestamp, 'HH24') 
), b AS (
    SELECT 
     ROW_NUMBER() OVER (PARTITION BY hour ORDER BY ctn DESC) rn, 
     thename, hour, cnt 
    FROM a 
) 
SELECT * 
FROM b 
WHERE rn < 20