题目:写一个sql语句查询各个岗位分数的平均数,并且按照分数降序排序,

结果保留小数点后面3位(3位之后四舍五入);

思路:group by分组job,按照job进行分数score算平均avg

select job, round(AVG(score), 3) as avg from grade group by job order by avg desc