重点内容修改下列脚本mysql_practice.sql，进行练习mysql基本操作：

show databases;create database if not exists `HA`;use HA;create table if not exists student (id int, name char(40), age int);show create table student \G;desc student;create table student2 (id int(20), name char(40), age int) ENGINE=InnoDB DEFAULT CHARSET=utf8;show columns from student2;drop table student2;alter table student rename students;show tables;alter table students modify id int(10);show fields from students;alter table students modify id int(20) primary key;show fields from students;alter table students change name stname char(20);desc students;alter table students add sex enum('M','W');desc students;alter table students add uid int(10) first;desc students;alter table students add address char(50) after age;desc students;alter table students drop address;insert into students values(1,1,'liqiang',22,'M');insert into students(uid,id) values(2,2);select * from students;select uid,id from students;select * from HA.students \G;show tables;drop table if exists students;show tables;show databases;drop database if exists `HA`;show databases;