使用分层查询和过滤器仅获取叶节点。

Oracle安装程序 ：

CREATE TABLE table_name ( bom_code, rm_code, qty ) AS
  SELECT 'A', 'B', 1 FROM DUAL UNION ALL
  SELECT 'A', 'C', 2 FROM DUAL UNION ALL
  SELECT 'A', 'D', 5 FROM DUAL UNION ALL
  SELECT 'A', 'E', 3 FROM DUAL UNION ALL
  SELECT 'A', 'F', 8 FROM DUAL UNION ALL
  SELECT 'D', 'G', 2 FROM DUAL UNION ALL
  SELECT 'D', 'H', 1 FROM DUAL UNION ALL
  SELECT 'D', 'I', 1 FROM DUAL UNION ALL
  SELECT 'D', 'J', 1 FROM DUAL UNION ALL
  SELECT 'F', 'K', 1 FROM DUAL UNION ALL
  SELECT 'F', 'L', 1 FROM DUAL UNION ALL
  SELECT 'G', 'Z', 1 FROM DUAL UNION ALL
  SELECT 'G', 'AA', 3 FROM DUAL UNION ALL
  SELECT 'I', 'M', 4 FROM DUAL UNION ALL
  SELECT 'I', 'N', 9 FROM DUAL UNION ALL
  SELECT 'I', 'O', 7 FROM DUAL UNION ALL
  SELECT 'N', 'P', 6 FROM DUAL UNION ALL
  SELECT 'N', 'Q', 12 FROM DUAL UNION ALL
  SELECT 'N', 'R', 4 FROM DUAL UNION ALL
  SELECT 'N', 'S', 9 FROM DUAL UNION ALL
  SELECT 'S', 'T', 3 FROM DUAL UNION ALL
  SELECT 'S', 'U', 2 FROM DUAL UNION ALL
  SELECT 'T', 'V', 1 FROM DUAL UNION ALL
  SELECT 'T', 'W', 3 FROM DUAL UNION ALL
  SELECT 'U', 'X', 5 FROM DUAL UNION ALL
  SELECT 'U', 'Y', 8 FROM DUAL;

查询 ：

SELECT t.*,
       SYS_CONNECT_BY_PATH( BOM_CODE, '-' ) || '-' || RM_CODE AS path,
       LEVEL
FROM   table_name t
WHERE  CONNECT_BY_ISLEAF = 1
START WITH bom_code = 'A'
CONNECT BY PRIOR rm_code = bom_code;

输出 ：

```
BOM_CODE | RM_CODE | QTY | PATH | LEVEL
:------- | :------ | –: | :------------- | ----:
A | B | 1 | -A-B | 1
A | C | 2 | -A-C | 1
G | AA | 3 | -A-D-G-AA | 3
G | Z | 1 | -A-D-G-Z | 3
D | H | 1 | -A-D-H | 2
I | M | 4 | -A-D-I-M | 3
N | P | 6 | -A-D-I-N-P | 4
N | Q | 12 | -A-D-I-N-Q | 4
N | R | 4 | -A-D-I-N-R | 4
T | V | 1 | -A-D-I-N-S-T-V | 6
T | W | 3 | -A-D-I-N-S-T-W | 6
U | X | 5 | -A-D-I-N-S-U-X | 6
U | Y | 8 | -A-D-I-N-S-U-Y | 6
I | O | 7 | -A-D-I-O | 3
D | J | 1 | -A-D-J | 2
A | E | 3 | -A-E | 1
F | K | 1 | -A-F-K | 2
F | L | 1 | -A-F-L | 2

**查询2** ：

如果要沿路径计算总量，请使用相关子查询以相反的方式遍历层次结构：



    SELECT t.*,
           SYS_CONNECT_BY_PATH( BOM_CODE, '-' ) || '-' || RM_CODE AS path,
           LEVEL,
           ( SELECT SUM( qty )
             FROM   table_name s
             START WITH t.rm_code = s.rm_code
             CONNECT BY PRIOR bom_code = rm_code ) AS total_qty
    FROM   table_name t
    WHERE  CONNECT_BY_ISLEAF = 1
    START WITH bom_code = 'A'
    CONNECT BY PRIOR rm_code = bom_code;


**输出** ：

> ```
BOM_CODE | RM_CODE | QTY | PATH           | LEVEL | TOTAL_QTY
:------- | :------ | --: | :------------- | ----: | --------:
A        | B       |   1 | -A-B           |     1 |         1
A        | C       |   2 | -A-C           |     1 |         2
G        | AA      |   3 | -A-D-G-AA      |     3 |        10
G        | Z       |   1 | -A-D-G-Z       |     3 |         8
D        | H       |   1 | -A-D-H         |     2 |         6
I        | M       |   4 | -A-D-I-M       |     3 |        10
N        | P       |   6 | -A-D-I-N-P     |     4 |        21
N        | Q       |  12 | -A-D-I-N-Q     |     4 |        27
N        | R       |   4 | -A-D-I-N-R     |     4 |        19
T        | V       |   1 | -A-D-I-N-S-T-V |     6 |        28
T        | W       |   3 | -A-D-I-N-S-T-W |     6 |        30
U        | X       |   5 | -A-D-I-N-S-U-X |     6 |        31
U        | Y       |   8 | -A-D-I-N-S-U-Y |     6 |        34
I        | O       |   7 | -A-D-I-O       |     3 |        13
D        | J       |   1 | -A-D-J         |     2 |         6
A        | E       |   3 | -A-E           |     1 |         3
F        | K       |   1 | -A-F-K         |     2 |         9
F        | L       |   1 | -A-F-L         |     2 |         9

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