编辑代码

create database  test
       default character set uft8;
      show databases;   

 use test;
 create table student(
 sno char(9) primary key,
 sname char(20),
 ssex char(2),
 sage smallint,
 sdept char(40),
 saddr char(100)
 );    

 select * from student
 insert into student(sno,sname,ssex,sage,sdept,saddr)
 values('2022308097','李珊珊','女',18,'jk','b209'),
 insert into student(sno,sname,ssex,sage,sdept,saddr)
 values
 ('2022308093''陈政怡','女',18,'ps','b209'),
 ('2022308095''曹馨月','女',18,'ks','b209'),
 ('2022308099''覃雅思','女',18,'dy','b209'),

 select * from student;
 selct *
 from student
 where sdept='dy'

 select count(*)
 from student;

 update student
 set sage=sage-1
 where sname=‘李珊珊’;

 delete
 from test
 where grade is null;