数据库编译约束

use masterif exists (select * from sysdatabases where name='myschool')drop database myschoolcreate database myschoolon primary(name='myschool_data',filename='D:\\myschool_data.mdf',size=5mb,maxsize=100mb,filegrowth=15%)log on(name='myschool_log',filename='D:\\myschool_log.ldf',size=2mb,filegrowth=1mb)use myschoolcreate table student(studentid int not null,studentname varchar(10) not null,studentage int not null,studentremark varchar(50) null,gradeid int not null)use myschoolcreate table grade(gradeid int identity(1,1),gradename varchar(20))alter table studentadd constraint PK_studentid primary key(studentid)--alter table grade--add constraint PK_gradeid primary key(gradeid)alter table studentadd constraint FK_gradeid foreign key(gradeid)references grade (gradeid)goinsert into student (studentid,studentname,studentage,studentremark,gradeid)values(1,'陈',20,'xxxx',1)insert into student (studentid,studentname,studentage,studentremark,gradeid)values(2,'陈1',20,'xxxx',1)insert into grade(gradename)values('s1'),('s2'),('y2')