Select查询语句按以下顺序处理：
1.FROM 2.WHERE 3.GROUP BY 4.HAVING//含有 HAVING COUNT(*)>1 即保留多个数量的 5.SELECT 6.ORDER BY
书写顺序却是：
1.SELECT 2.FROM 3.WHERE 4.GROUP BY 5.HAVING 6.ORDER BY
常用SQL
原文：https://www.cnblogs.com/cdjbolg/p/11759322.html
