数据库建表,建约束,建外键

use stu

Create Table Course(

CID Varchar(12)Not Null Primary Key,

CName Varchar(20)Not Null Unique, CCridet Varchar(20)Not Null

);

Select*from Course

--利用命令为表Course创建主键

Alter Table Course

Add Constraint PK_CNo

Primary Key(CID,CName)

--删除约束

Alter Table Course Drop Constraint UQ__Course__0425A276

--利用语句增加Unique约束

Alter Table Course Add Constraint Ue_Cname

Unique(CName)

--增加Default约束

Alter Table Course Add Constraint

UD_Credit

Default'内蒙古呼和浩特'For CCridet

--插入新的记录

Insert Into Course

Values('001','OOP',Default) Select*from Course

Insert Into Course(CID,CName) Values('002','OOO')

select*from Course

--如果利用Insert 语句指定特定的列时，必须包含

--不能为空的所有列(不能为空但定义了Default约束

--除外)

Create Table Stu(

SID Varchar(12)Not Null, SName Varchar(12)Not Null, SSex Char(2)Not Null

)

Select*From Stu

Alter Table Stu Add COnstraint

UD_Sex

Default'男'For SSex

Insert Into Stu(SID,SName)

Values('001','Herry')

Select*From Stu

--TimeStamp时间戳

--Identity

Create Table Class(

CID Int Identity(1,2),

CAddress Varchar(20)Not Null

)

Insert Into Class(CAddress)

Values('恶人都是')

Select*from Class

Delete From Class Where CID = 33 --创建成绩表Score

Create Table Score(

CID Varchar(12)Not Null Primary Key,--成绩编号

CNumber Varchar(12)Not Null,--学

号

CName Varchar(20)Not Null,--课程名称

CScore Decimal(5,2)Not Null

)

Select*From Score

--创建CHeck 约束

Alter Table Score

Add Constraint CK_Brand Check (CScore between 0 and 100)

Insert Into Score

Values('34','34','34',10.00) select*from Score

--Foreign Key外键

--创建员工表Employee和工资表Salary Create Table Employee

(

EID Varchar(12)Not Null Primary Key,--员工号

EName Varchar(20)Not Null--员工姓名

)

Create Table Salary(

SID Varchar(12)Not Null Primary Key,--工资编号

EID Varchar(12)Not Null

)

Alter Table球队名Add Constraint FK_球队名

Foreign Key(球队名)References球队表(球队名)