表的弱联系 

1 select t.stuid, t.stuname, t.classcode, t1.classname, t1.grade
2   from astudents t, aclass_lj t1
3  where t.classcode(+) = t1.classcode;

select t.stuid, t.stuname, t.classcode, t1.classname, t1.grade
  from astudents t, aclass_lj t1
 where t.classcode = t1.classcode(+);

posted @ 2017-07-19 11:43  liujiee2  阅读(83)  评论(0)  编辑  收藏  举报