聚合函数

最小值
select min(score) from dbo.Table_3;

最大值
select max(score) from dbo.Table_3;

求总数
select count(*) from dbo.Table_3;

求合格人数
select count(1) from dbo.Table_3 where score>=60;

求总人数
select count(1) from dbo.Table_3;