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玩龙天子 发表于 2018-10-11 10:22:09

mysql 优化语句

　　优化前：
select b.type, ifnull(count(0),0) as qty from b_sell_quotationd a,b_sell_quotation b　　
where b.quotationNo=a.quotationNo and a.status='N' and b.companycode='XXXXX' AND b.type='general';
　　优化后：
　　selectCOUNT(0) from b_sell_quotationd a LEFT JOIN (SELECT * FROM b_sell_quotation WHERE type='general') b ON b.quotationNo=a.quotationNo WHERE b.companycode='XXXXXX' and a.status='N'

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