建表

建表语句：
CREATE TABLE student(
    id int not null,
    name char(12),
    sex char(1)
);

预置数据
insert into student values(1, 'wh', 1);
insert into student values(2, 'wh1', 0);
insert into student values(3, 'zyx', 0);

commit; 

 增加字段
alter  table student  add shuxue int ;
更新语句
update  student set shuxue = 60 where id = 1;
update  student set shuxue = 80 where id = 2;
update  student set shuxue = 90 where id = 3;

 

select sex as gender, count(*), avg(shuxue), sum(shuxue) from student group by sex;

select sex,count(*)from student group by sex;