여러 선택 대신 case 문

Question

아래 코드 중 몇 가지 진술이 있는데이 방법을 훨씬 간단하고 쉽게 작성하는 방법을 찾으려고합니다. 나는 CASE 문이 최선이라고 생각할 것이다. 그러나 몇 일간의 시행 착오 후에 나는 그렇게하는 법을 알 수 없었다. 모든 도움 및/또는 설명은 크게 감사하겠습니다.

select Count(lcs.statename) as [Name 1] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Follow Up' 
    AND lcnum = '412' 
    AND status = '0' 
select Count(lcs.statename) as [Name 2] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Initial Review' 
    AND lcnum = '412' 
    AND status = '0' 
select Count(lcs.statename) as [Name 3] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Execution' 
    AND lcnum = '412' 
    AND status = '0' 
select Count(lcs.statename) as [Name 4] 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    where lcs.statename = 'Holdback' 
    AND lcnum = '412' 
    AND status = '0' 

Answer 1

시도 뭔가 같은 :

SELECT SUM(CASE WHEN lcs.statename = 'Follow Up' THEN 1 ELSE 0 END) as [Name 1], 
    SUM(CASE WHEN lcs.statename = 'Initial Review' THEN 1 ELSE 0 END) as [Name 2], 
    SUM(CASE WHEN lcs.statename = 'Execution' THEN 1 ELSE 0 END) as [Name 3], 
    SUM(CASE WHEN lcs.statename = 'Holdback' THEN 1 ELSE 0 END) as [Name 4] 
FROM hsi.itemlc as ilc 
LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
WHERE lcnum = '412' 
AND status = '0' 

Answer 2

당신은 SUM (함께 할 수있는)과 CASE :

SELECT 
     SUM(CASE WHEN lcs.statename = 'Follow Up' THEN 1 ELSE 0 END) as [Name 1], 
     SUM(CASE WHEN lcs.statename = 'Initial Review' THEN 1 ELSE 0 END) as [Name 2], 
     ... 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    WHERE lcnum = '412' AND status = '0'; 

또는 여러 행을 읽을 수 있는지, 당신이 사용할 수 GROUP BY :

SELECT lcs.statename, COUNT(*) AS num 
    FROM hsi.itemlc as ilc 
    LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
    WHERE lcnum = '412' AND status = '0' 
    GROUP BY lcs.statename; 

이는 다음과 같이의 SUM() 기능 CASE 문을 사용할 수 있습니다

Follow Up  25 
Initial Review 17 
... 

Answer 3

처럼 U 뭔가 :

SELECT SUM(CASE WHEN lcs.statename = 'Follow Up' THEN 1 ELSE 0 END) as [Name 1], 
     SUM(CASE WHEN lcs.statename = 'Initial Review' THEN 1 ELSE 0 END) as [Name 2], 
     SUM(CASE WHEN lcs.statename = 'Execution' THEN 1 ELSE 0 END) as [Name 3], 
     SUM(CASE WHEN lcs.statename = 'Holdback' THEN 1 ELSE 0 END) as [Name 4] 
FROM hsi.itemlc as ilc 
LEFT JOIN hsi.lcstate as lcs on lcs.statenum = ilc.statenum 
WHERE lcnum = '412' 
    AND status = '0' 

각 상태 이름의 조건 카운트 초래한다.