SQL学习系列之对执行计时
---SQL执行计时
declare @date1 datetime
declare @date2 datetime
select @date1=getdate()
--测试语句
select @date2=getdate()
select datediff(millisecond, @date1, @date2)
--结果是毫秒数
---用EXISTS替代IN、用NOT EXISTS替代NOT IN
where Sendorder.person_id not in(select user_id from reg_person ) or Sendorder.worksite_id not in(select id from worksite) order by Sendorder.addtime desc
---40109.38毫秒
where not EXISTS (SELECT id FROM reg_person where reg_person.user_id=Sendorder.person_id) or not EXISTS (SELECT id FROM worksite where worksite.id=Sendorder.worksite_id) order by Sendorder.addtime desc
---8531.25毫秒
declare @date1 datetime
declare @date2 datetime
select @date1=getdate()
--测试语句
select @date2=getdate()
select datediff(millisecond, @date1, @date2)
--结果是毫秒数
---用EXISTS替代IN、用NOT EXISTS替代NOT IN
where Sendorder.person_id not in(select user_id from reg_person ) or Sendorder.worksite_id not in(select id from worksite) order by Sendorder.addtime desc
---40109.38毫秒
where not EXISTS (SELECT id FROM reg_person where reg_person.user_id=Sendorder.person_id) or not EXISTS (SELECT id FROM worksite where worksite.id=Sendorder.worksite_id) order by Sendorder.addtime desc
---8531.25毫秒
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/16436858/viewspace-539636/ ，如需转载，请注明出处，否则将追究法律责任。
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