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(+);
原文：http://www.cnblogs.com/liujie-e2/p/7204926.html