MySql 链接查询时加入count，avg等操作时的方法

当sql语句要查询总数又同时要查询其他数据时，加上ROUND()

select a.*,ROUND(AVG(b.s_score),2),ROUND(count(b.s_score)) from

student a 
left join score b on b.s_id=a.s_id GROUP BY b.s_id HAVING ROUND(AVG(b.s_score),2)>60