写出发帖数最多的十个人名字的SQL，利用下表posts(id ,username, content)【id：序号，username：用户名，content：文章内容】
select username,count(username) as total from posts GROUP BY username order by total desc limit 10写出发帖数最多的十个人名字的SQL，利用下表posts(id ,username, content)【id：序号，username：用户名，content：文章内容】
select username,count(username) as total from posts GROUP BY username order by total desc limit 10