摘要: ###1.数据库 select a.class,e.course,avg(e.score) from account as a,exam as e where a.id=e.aid group by a.class,e.course; ###2.linux 1.如何清空a.log文件 echo > 阅读全文
posted @ 2020-12-17 18:51 霖尤li 阅读(225) 评论(0) 推荐(0) 编辑