创建edu数据库中的三张表：student、course、sc，并设置合理的完整性约束。其表结构分别如下：答：use __1_;create __2__ student(sno char(10) primary key ,sname varchar(8) not null,ssex enum('男','女'),sbirthday date,___3___ ___4___speciality varchar(20));create table ___5___cno char(5) primary key ,___6__ ___7___ not null);create table sc(sno char(10) not null,cno char(5) not null,___8__ ___9__primary key(sno,cno),foreign key(sno) references student(__10__),foreign key(cno) references course(cno));