기간 동안 평균을 계산하려면 어떻게해야합니까?

Question

나는 한 기간 동안 평균을하려고합니다 (예 : 지난 6 개월, 지난 달, 지난 주 ...).

나는 4 개의 검색어를 만들었습니다. 내가 명확하게 할 수 있을까?

/** ON SELECTED DATE*/ 
SELECT AVG(RUN_TIME) 
FROM (SELECT (DATEDIFF(minute,MIN(CAST(START_DATE AS DATETIME)), MAX(CAST(END_DATE AS DATETIME)))) as RUN_TIME FROM TableTest where DATE_EXPECTED = DATE_SELECTED) f 

/**ON 6 last month*/ 
SELECT AVG(RUN_TIME) 
FROM (SELECT (DATEDIFF(minute,MIN(CAST(START_DATE AS DATETIME)), MAX(CAST(END_DATE AS DATETIME)))) as RUN_TIME FROM TableTest 
where Month(CAST(DATE_SELECTED AS DATETIME)) BETWEEN Month(CAST(DATE_SELECTED AS DATETIME)) AND Month(CAST(DATE_SELECTED AS DATETIME))+6) f 

/** on 30 last days */ 
SELECT AVG(RUN_TIME) 
FROM (SELECT (DATEDIFF(minute,MIN(CAST(START_DATE AS DATETIME)), MAX(CAST(END_DATE AS DATETIME)))) as RUN_TIME FROM TableTest where DATE_EXPECTED between DATE_SELECTED and DATE_SELECTED+30) f 

/* on 5 last days */ 
SELECT AVG(RUN_TIME) 
FROM (SELECT (DATEDIFF(minute,MIN(CAST(START_DATE AS DATETIME)), MAX(CAST(END_DATE AS DATETIME)))) as RUN_TIME FROM TableTest where DATE_EXPECTED between DATE_SELECTED and DATE_SELECTED+5) f 

작동하지만 최선의 방법으로이 작업을 수행 할 수 있는지 알고 싶습니다.

감사합니다,

Answer 1

조건부 집계를 사용할 수 있습니다

SELECT AVG(CASE WHEN DATE_EXPECTED = DATE_SELECTED THEN RUN_TIME END) as avg_1, 
     AVG(CASE WHEN Month(CAST(DATE_SELECTED AS DATETIME)) BETWEEN Month(CAST(DATE_SELECTED AS DATETIME)) AND Month(CAST(DATE_SELECTED AS DATETIME))+6 THEN RUN_TIME END) as avg_2, 
     AVG(CASE WHEN DATE_EXPECTED between DATE_SELECTED and DATE_SELECTED+30 THEN RUN_TIME END) as avg_3, 
     AVG(CASE WHEN DATE_EXPECTED between DATE_SELECTED and DATE_SELECTED+5 THEN RUN_TIME END) as avg_4 
FROM (SELECT (DATEDIFF(minute,MIN(CAST(START_DATE AS DATETIME)), MAX(CAST(END_DATE AS DATETIME)))) as RUN_TIME 
     FROM TableTest 
    ) f;