在11g中
SQL> select count(*)
2 from emp a, dept b, bonus c
3 where a.deptno(+) = b.deptno
4 and a.ename(+) = c.ename;
where a.deptno(+) = b.deptno
*
ERROR at line 3:
ORA-01417: a table may be outer joined to at most one other table
SQL>
在12C中
SQL> select count(*)
2 from emp a, dept b, bonus c
3 where a.deptno(+) = b.deptno
4 and a.ename(+) = c.ename;
COUNT(*)
----------
0
SQL>
Oracle 12C -- native left outer join的加强
原文：http://www.cnblogs.com/abclife/p/4717962.html
