create table student
(
	Sno char(9) primary key,
	Sname char(20) unique,
	Ssex char(2),
	Sage smallint,
	Sdept char(20)

);

//查询
select Sno,Sname,Ssex,Sage,Sdept from student where Sname='wy';

//插入
insert into student values('3','dh','v','12','jg');
insert into student values('4','fg','n','45','sp');

insert into student values('5','hg','n','25','dp');
insert into student values('6','fg','v','55','ep');
insert into student values('7','rg','n','66','tp');
//删除
delete Student where Sname='hg';


//更新
update student set Sname='zl' where Sname='fg' and Ssex='n';