怎样建立数据库以及数据表，以及表中数据项的更改

if exists(select * from sys.sysdatabases where [name] = 'DB_Student')
drop database DB_Student
go

create database DB_Student
on
(
    name = DB_Student_mdf,
    filename = 'E:DB_Student_mdf.mdf',
    size = 3mb,
    maxsize = 100mb,
    filegrowth=1mb
)
log on
(
    name = DB_Student_ldf,
    filename = 'E:DB_Student_ldf.mdf',
    size = 3mb,
    maxsize = 100mb,
    filegrowth = 1mb
)

use DB_Student
if exists(select * from sys.objects where [name] = 'T_userInfo' )
drop table T_userInfo
go

use DB_Student
create table T_userInfo
(
    stuName varchar(20),
    stuId varchar(20) primary key,
    score float,
    sex varchar(4)
)

alter table T_userInfo
add hobby varchar(20)
go

alter table T_userInfo
alter column hobby varchar(25)
go

use DB_Student

exec sp_rename 'T_userInfo.hobby','hobbys'
go

alter table T_userInfo
drop column hobbys
go