有关数据库查询的问题
求大神讲解，感谢感谢
select count(*) from employee where '绩效分数'>=80
select '姓名','部门' from employee order by '绩效分数' desc limit 3;
select '部门',avg('绩效分数') as '平均绩效' from employee group by '部门'
select count(*) from employee where '绩效分数'>=80
select '姓名','部门' from employee order by '绩效分数' desc limit 3;
select '部门',avg('绩效分数') as '平均绩效' from employee group by '部门'