标签：campaign open code blog rom let div category from
使用EXISTS(或NOT EXISTS)通常将提高查询的效率，由于NOT IN子句将对子查询中的表执行了一个全表遍历。
ms ssql 实例：
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
标签：campaign open code blog rom let div category from
原文地址：http://www.cnblogs.com/zoro-zero/p/7454263.html
