sql case語句或if語句

Question

嗨，我正在做一個簡單的sql報告，不能把我的頭放在如何做這個簡單的case語句上。 @risk的參數為1或0。 如果存在風險，則返回所有風險大於0的記錄；如果沒有風險，則返回所有安全記錄> 0

SELECT count(b.observationid), a.NumAtRisk , a.CBICode, c.Observerid, d.CBIDescription, d.CBIcatID
FROM dbo.ObservationDetails a
JOIN dbo.Observation b
    ON a.ObservationID = b.ObservationID
join #Temp c 
    on c.Observerid = b.ObserverID
join CBI d
on a.cbiid = d.cbiID
where b.ObservationDate between @Begdate and @Enddate 


-- Parameter needs to return one or the other......................
and case when  
(@risk) = 1  then [a.NumAtRisk] > 0  
     else [a.NumSafe] > 0 

     end    

Answer 1

像這樣：

where (@risk = 1 and a.NumAtRisk > 0) or
      (@risk = 0 and a.NumSafe > 0)

不需要case表達。