-- 查询1：
11:18:52 SCOTT@tdwora > select rownum rn, t__.* from (
11:19:46   2  select e.deptno, e.ename, d.deptno, d.loc
11:19:46   3  from emp e, dept d
11:19:46   4  where e.deptno=d.deptno ) t__;
select rownum rn, t__.* from (
                      *
第 1 行出现错误:
ORA-00918: 未明确定义列


-- 查询2(将查询1中的子查询涉及到的两个同名字段 deptno去掉一个)

11:19:47 SCOTT@tdwora > select rownum rn, t__.* from (
11:20:11   2  select e.deptno, e.ename, d.loc
11:20:11   3  from emp e, dept d
11:20:11   4  where e.deptno=d.deptno ) t__;

        RN     DEPTNO ENAME      LOC
---------- ---------- ---------- -------------
         1         10 KING       NEW YORK
         2         10 CLARK      NEW YORK
         3         20 FORD       DALLAS
         4         20 ADAMS      DALLAS
         5         20 JONES      DALLAS
         6         20 SMITH      DALLAS
         7         30 BLAKE      CHICAGO
         8         30 MARTIN     CHICAGO
         9         30 WARD       CHICAGO
        10         30 TURNER     CHICAGO
        11         30 ALLEN      CHICAGO

已选择11行。

------解决方案--------------------

select * from users us, post pt,state se,branch bh 
 where us.branch_id=bh.branch_id   and us.post_id=pt.post_id   
 and us.state_id=se.state_id  
 and bh.branch_name like '%' 
 and pt.post_name like '%'
 and us.users_name like '%'
 and us.users_id like '%'

你查询结果里 包含了重复的字段（标红）