use SchoolDB

Go

-- 创建学生表

Create Table Student(

	StuID varchar(10) primary key,

	StuName nvarchar(50) not null,

	StuEnName varchar(50) not null unique,

	StuAge int,

	StuBirthday datetime,

	StuSex nvarchar(10) default('男')

)

--教师表

Create Table Teacher(

	TeaID varchar(10) primary key,

	TeaName nvarchar(50) not null,

	TeaEnName varchar(50) not null unique,

	TeaAge int,

	TeaBirthday datetime,

	TeaSex nvarchar(10) default('男')

)

--课程表

Create Table Course(

	CouID varchar(10) primary key,

	CouName nvarchar(50) not null unique,

	TeaID varchar(10) foreign key(TeaID) references  Teacher(TeaID)

)

--成绩表

Create Table Score(

	StuID varchar(10) foreign key(StuID) references Student(StuID),

	CouID varchar(10) foreign key(CouID) references Course(CouID),

	Score Decimal(18,1),

)

-- 新增字段

alter Table Student

add

column_1 varchar(10) NULL

-- 删除字段

alter Table Student

drop  Column column_1  

-- 删除主、外键约束

alter Table Course

drop  CONSTRAINT  FK__Course__TeaID__1920BF5C  

-- 删除主、外键约束

alter Table Course

add  CONSTRAINT  FK__Course__TeaID__1920BF5C   foreign key(TeaID)  References Teacher(TeaID)