编辑代码

show DATABASES;
CREATE DATABASE test; 
show DATABASES;
use test;
CREATE TABLE student(
   XMH int not null,
   YJSBH int,
   XMM varchar(30),
   JF varchar(30),
    primary key(XMH,YJSBH)
);
INSERT INTO student VALUES(1,1,'项目一','10万');
INSERT INTO student VALUES(2,12,'项目二','20万');
INSERT INTO student VALUES(3,123,'项目三','30万');
delete from student where XMH=3;

update student set YJSBM=13 where XMH=2;
insert into student(XMH,YJSBH,XMH,JF)
values(4,1234,'项目四'，'40万');
SELECT   *  FROM  student;

alter table  student add  jingfe varchar(30);
desc student;

alter table student MODIFY XMM varchar(40);
desc student;

alter table student CHANGE XMM xiangmuming varchar(40);
desc student;

SELECT * from student where XMM like '六%';
update student set zhuchezhibeng='5000元' where XMH=1;