2015/4/2 sql数据库创建表 表的关联

1.建立一个“学生”表 Student

create table student_muanfeng(

sno char(4) primary key(主键),

Sname char(20) unique（为约束）,

Ssex char(2) null check(sex in('M','F')),

Sage smallint null check(age>18 and age<25),

Sdept char(20)

);

2.建立一个“课程”表Course

Create table Course(

Cno char(4) primary key,

Cname char(40),

Credit smallint null check(credit>0 and credit<10)

);

)

3，建立学生学生选课表 SC

Create table SC 

sno char(4) not null ,cno char(4) not null primary key(sno,cno),
grade smallint null check(grade>0 and grade <100))
alter table SC add constraint fk_sno foreign key(sno) references Student(sno);
alter table SC add constraint fk_cno foreign key(cno) references Course(cno);

2.Create table SC（

Sno char(4),

Cno Char(4),

Primary key (Sno,Cno),

Frimary key(Sno) reference student(Sno),

Frimary key(Cno) reference Course(Cno),

);

 插入数据：

insert into 表名称（条件）value(相对应的值)