参考表
count()用来统计记录的条数 代码如下:mysql> select count(*) from score;mysql> select count(*) from score where stu_id=901;
sum()求和函数 代码如下:mysql> select sum(grade) from score;mysql> select id,sum(grade) from score where stu_id=901;
avg()求平均值函数 代码如下:mysql> select avg(grade) from score where c_name=’计算机’;mysql>
