优化前：
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1
2
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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';
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优化后：
select COUNT(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'
本文转自yunlielai51CTO博客，原文链接：http://blog.51cto.com/4925054/1883231，如需转载请自行联系原作者