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SQL语句NOT IN优化之换用NOT EXISTS

日期：2018-10-15点击：473收藏

NOT IN查询示例（示例背景描述：根据条件查询Questions表得到的数据基本在PostedData表中不存在，为完全保证查询结果在PostedData表中不存在，使用NOT IN）：

SET STATISTICS PROFILE ON; SET STATISTICS IO ON; SET STATISTICS TIME ON; GO /*--你的SQL脚本开始*/ SELECT A.Id FROM dbo.Questions A WITH ( NOLOCK ) WHERE A.QuestionState = '正常' AND A.CheckTime > '2018-09-29 16:00:00' AND A.StateShowID NOT IN ( SELECT B.IntId FROM dbo.PostedData B WHERE B.[Type] = 'question' ); /*你的SQL脚本结束*/ GO SET STATISTICS PROFILE OFF; SET STATISTICS IO OFF; SET STATISTICS TIME OFF;

查询耗时如图：

换用NOT EXISTS 查询示例：

SET STATISTICS PROFILE ON; SET STATISTICS IO ON; SET STATISTICS TIME ON; GO /*--你的SQL脚本开始*/ SELECT A.Id FROM dbo.Questions A WITH ( NOLOCK ) WHERE A.QuestionState = '正常' AND A.CheckTime > '2018-09-29 16:00:00' AND NOT EXISTS ( SELECT B.IntId FROM dbo.PostedData B WHERE B.[Type] = 'question' AND A.StateShowID = B.IntId ); /*你的SQL脚本结束*/ GO SET STATISTICS PROFILE OFF; SET STATISTICS IO OFF; SET STATISTICS TIME OFF;