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  • sql not in 优化问题

    问题情境:

      not in 耗时过长。想用join或exits代替。结果并不明显,这里先记录3种写法,以后探讨速度问题。

    sql语句:

                        // not exists
                        sql = @"select c.customerid, c.customername, c.sex, c.birthday, c.CustomerNumber, s.CreateTime, d.description, s.seriesID
                                from customerinfo c, seriestable s, sitecode d
                                where s.customerid = c.customerid
                                and s.createsite = d.siteid
                                and not exists  
                                (select 1 from customer_healthinfo h where h.customerid = c.customerid) 
                                order by s.CreateTime";
                        //not in
                        sql = @"select c.customername, c.sex, c.birthday, c.CustomerNumber, s.CreateTime, d.description, s.seriesID
                                from customerinfo c, seriestable s, sitecode d
                                where s.customerid = c.customerid
                                and s.createsite = d.siteid
                                and c.customerid not in  
                                (select customerid from customer_healthinfo) order by s.CreateTime";
                        //left join
                        sql = @"select customername, sex, birthday, CustomerNumber, tempA.CreateTime, tempA.description, tempA.seriesID
                                from 
                                (select c.customerid, c.customername, c.sex, c.birthday, c.CustomerNumber, s.CreateTime, d.description, s.seriesID
                                from customerinfo c, seriestable s, sitecode d
                                where s.customerid = c.customerid
                                and s.createsite = d.siteid) as tempA left join customer_healthinfo h 
                                on tempA.customerid = h.customerid
                                where h.customerid is null 
                                order by CreateTime";
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  • 原文地址:https://www.cnblogs.com/gaara-zhang/p/10695436.html
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