-- mapping strong entity

create table Students (
	-- stuID    char(7) check (stuID ~ '[0-9]{7}'),
	stuID       integer check (studID between 3000000 and 5999999),
	name        varchar(100) not null,
	degree      char(4) not null check (degree ~ '^[0-9]{4}$'),
	primary key (stuID)
);

