drop table if exists t_student;
		drop table if exists t_class;

		create table t_class(
			cno int,
			cname varchar(255),
			primary key(cno)
		);

		create table t_student(
			sno int,
			sname varchar(255),
			classno int,
			foreign key(classno) references t_class(cno)
		);

		insert into t_class values(101,'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx');
		insert into t_class values(102,'yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy');

		insert into t_student values(1,'zs1',101);
		insert into t_student values(2,'zs2',101);
		insert into t_student values(3,'zs3',102);
		insert into t_student values(4,'zs4',102);
		insert into t_student values(5,'zs5',102);
		insert into t_student values(6,'zs6',102);
		select * from t_class;
		select * from t_student;