摘要: 1、count distinct 优化 --优化前 select count(distinct id )from tablename --优化后 select count(1) from (select distinct id from tablename)tmp; select count(1) 阅读全文
posted @ 2019-12-24 18:14 singsong~ 阅读(517) 评论(0) 推荐(0) 编辑