1.select 语句的执行顺序 SELECT a.id,a.`product_name`,a.`agreement_copies` i,b.id as statusId from `opmp_product_info` a left join `total_status` b on a.`id`=b.order_id group by a.`product_name` having i > 40 order by i limit 50 使用 AS allias_name 可以给列指定别名.可…