drop table articles cascade constraints;
create table articles (
  aid varchar2(20),
  jname varchar2(200),
  vol number(2),
  num number(2),
  spage number(4),
  epage number(4),
  title varchar2(256),
  primary key (aid)
);

drop table authors cascade constraints;
create table authors (
  aid varchar2(20),
  aname varchar2(50),
  primary key (aid,aname),
  foreign key (aid) references articles
);