Question

我在oracle中尝试Hierarchical select查询但是不能从那里得到强烈的愿望并且不会在我写错了查询之前或者有错误在我的表中的数据我的愿望就像

I_ID    NAME    MGR_ID  LEVEL   PATH
1       SMITH       0    0      /SMITH
2       ALLEN       1    1      /SMITH/ALLEN
3       WARD        1    1      /SMITH/WARD
5       MARTIN      1    1      /SMITH/MARTIN
4       JONES       2    2      /SMITH/ALLEN/JONES
7       CLARK       2    2      /SMITH/ALLEN/CLARK
6       BLAKE       3    2      /SMITH/WARD/BLAKE
8       SCOTT       7    3      /SMITH/ALLEN/CLARK/SCOTT
9       KING        7    3      /SMITH/ALLEN/CLARK/KING
10      TURNER      8    4      /SMITH/ALLEN/CLARK/SCOTT/TURNER
12      JAMES       8    4      /SMITH/ALLEN/CLARK/SCOTT/JAMES
11      ADAMS       10   5      /SMITH/ALLEN/CLARK/SCOTT/TURNER/ADAMS
13      FORD        11   6      /SMITH/ALLEN/CLARK/SCOTT/TURNER/ADAMS/FORD
14      MILLER      13   7      /SMITH/ALLEN/CLARK/SCOTT/TURNER/ADAMS/FORD/MILLER

请帮助我参考check

Answer 1

我使用类似于你的查询，并将结果分组以仅为每个i_ids选择一行具有最大级别。

<强>查询：

select *
from (
    select
        i_id, name, mgr_id, max(plevel) - 1 "level",
        max(path) keep (dense_rank last order by plevel) path
from (
        select i_id, name, mgr_id, level plevel, SYS_CONNECT_BY_PATH(name, '/') path
        from emp
        connect by prior i_id = mgr_id
    )
group by i_id, name, mgr_id
)
order by "level", i_id

<强> Results ：

| I_ID |   NAME | MGR_ID | LEVEL |PATH                                              |
|------|--------|--------|-------|--------------------------------------------------|
|    1 |  SMITH |      0 |     0 |/SMITH                                            |
|    2 |  ALLEN |      1 |     1 |/SMITH/ALLEN                                      |
|    3 |   WARD |      1 |     1 |/SMITH/WARD                                       |
|    5 | MARTIN |      1 |     1 |/SMITH/MARTIN                                     |
|    4 |  JONES |      2 |     2 |/SMITH/ALLEN/JONES                                |
|    6 |  BLAKE |      3 |     2 |/SMITH/WARD/BLAKE                                 |
|    7 |  CLARK |      2 |     2 |/SMITH/ALLEN/CLARK                                |
|    8 |  SCOTT |      7 |     3 |/SMITH/ALLEN/CLARK/SCOTT                          |
|    9 |   KING |      7 |     3 |/SMITH/ALLEN/CLARK/KING                           |
|   10 | TURNER |      8 |     4 |/SMITH/ALLEN/CLARK/SCOTT/TURNER                   |
|   12 |  JAMES |      8 |     4 |/SMITH/ALLEN/CLARK/SCOTT/JAMES                    |
|   11 |  ADAMS |     10 |     5 |/SMITH/ALLEN/CLARK/SCOTT/TURNER/ADAMS             |
|   13 |   FORD |     11 |     6 |/SMITH/ALLEN/CLARK/SCOTT/TURNER/ADAMS/FORD        |
|   14 | MILLER |     13 |     7 |/SMITH/ALLEN/CLARK/SCOTT/TURNER/ADAMS/FORD/MILLER |

执行显示所有数据的分层查询

1 个答案: