使用EXISTS(或NOT EXISTS)通常將提高查詢的效率，由於NOT IN子句將對子查詢中的表執行了一個全表遍歷。

ms ssql 實例：

select 
subscriber_id
 
from 
NewsLetterSystem_CampaignCategorySubscriber ccs WITH ( NOLOCK )
where NOT EXISTS(
SELECT  distinct subscriber_id
FROM    NewsLetterSystem_OpenTracking ot WITH ( NOLOCK ) 
WHERE  ot.subscriber_id=ccs.subscriber_id and ot.campaign_id = 52801)
and ccs.campaign_id = 52801 and ccs.status_id = 1
 

Sql server not in優化