[转]Oracle查询树形数据的叶节点和子节点

oracle 9i判断是叶子或根节点，是比较麻烦的一件事情，SQL演示脚本如下:
--表结构--
DROP TABLE idb_hierarchical;  
create TABLE idb_hierarchical  
(  
id number,  
parent_id number,  
str varchar2(10)  
);  
--测试数据--  
insert into idb_hierarchical values(1,null,'A');  
insert into idb_hierarchical values(2,1,'B');  
insert into idb_hierarchical values(3,2,'C');  
insert into idb_hierarchical values(4,3,'D');  
insert into idb_hierarchical values(5,2,'E');  
insert into idb_hierarchical values(6,2,'F');  
insert into idb_hierarchical values(7,3,'G');  
insert into idb_hierarchical values(8,4,'H');  
insert into idb_hierarchical values(9,4,'I');  
insert into idb_hierarchical values(10,null,'J');  
insert into idb_hierarchical values(11,10,'K');  
insert into idb_hierarchical values(12,11,'L');  
insert into idb_hierarchical values(13,10,'M');  
[sql] view plaincopy
DROP TABLE idb_hierarchical;  
create TABLE idb_hierarchical  
(  
id number,  
parent_id number,  
str varchar2(10)  
);  
  
insert into idb_hierarchical values(1,null,'A');  
insert into idb_hierarchical values(2,1,'B');  
insert into idb_hierarchical values(3,2,'C');  
insert into idb_hierarchical values(4,3,'D');  
insert into idb_hierarchical values(5,2,'E');  
insert into idb_hierarchical values(6,2,'F');  
insert into idb_hierarchical values(7,3,'G');  
insert into idb_hierarchical values(8,4,'H');  
insert into idb_hierarchical values(9,4,'I');  
insert into idb_hierarchical values(10,null,'J');  
insert into idb_hierarchical values(11,10,'K');  
insert into idb_hierarchical values(12,11,'L');  
insert into idb_hierarchical values(13,10,'M');  
示例数据清单如下:

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SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,
        ID,PARENT_ID,LEVEL LVL  
         FROM idb_hierarchical  
          START WITH PARENT_ID IS NULL  
           CONNECT BY PARENT_ID = PRIOR ID;  
SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,
        ID,PARENT_ID,LEVEL LVL  
         FROM idb_hierarchical  
          START WITH PARENT_ID IS NULL  
           CONNECT BY PARENT_ID = PRIOR ID;  
表1:数据清单
STR_LEVEL    ID    PARENT_ID    LVL
+..A    1         1
+….B    2    1    2
+……C    3    2    3
+……..D    4    3    4
+……….H    8    4    5
+……….I    9    4    5
+……..G    7    3    4
+……E    5    2    3
+……F    6    2    3
+..J    10         1
+….K    11    10    2
+……L    12    11    3
+….M    13    10    2
在表1中，ID为8、9、 7、5、6、12、13都没有子节点，因此称为叶节点。

1.oracle9i 查询叶节点
只显示叶子节点SQL

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SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL  
  FROM idb_hierarchical I  
  --在oracle 9i中显示叶节点，需要判断是否有子节点即可  
  WHERE NOT EXISTS(SELECT 1  
  FROM idb_hierarchical B  
  WHERE I.ID=B.PARENT_ID)  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL  
  FROM idb_hierarchical I  
  --在oracle 9i中显示叶节点，需要判断是否有子节点即可  
  WHERE NOT EXISTS(SELECT 1  
  FROM idb_hierarchical B  
  WHERE I.ID=B.PARENT_ID)  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
表2
STR_LEVEL    ID    PARENT_ID    LVL
+……….H    8    4    5
+……….I    9    4    5
+……..G    7    3    4
+……E    5    2    3
+……F    6    2    3
+……L    12    11    3
+….M    13    10    2
显示所有节点，标明该行是否为叶节点SQL

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SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL,  
NVL((SELECT 'N'  
  FROM idb_hierarchical B  
  WHERE I.ID=B.PARENT_ID  
  AND ROWNUM  < 2),'Y') IS_LEAF  
  FROM idb_hierarchical I  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL,  
NVL((SELECT 'N'  
  FROM idb_hierarchical B  
  WHERE I.ID=B.PARENT_ID  
  AND ROWNUM  < 2),'Y') IS_LEAF  
  FROM idb_hierarchical I  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
表3
STR_LEVEL    ID    PARENT_ID    LVL    IS_LEAF
+..A    1         1    N
+....B    2    1    2    N
+......C    3    2    3    N
+........D    4    3    4    N
+..........H    8    4    5    Y
+..........I    9    4    5    Y
+........G    7    3    4    Y
+......E    5    2    3    Y
+......F    6    2    3    Y
+..J    10         1    N
+....K    11    10    2    N
+......L    12    11    3    Y
+....M    13    10    2    Y
oracle 9i 查询根节点
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SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL  
  FROM idb_hierarchical I  
 START WITH id =2  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL  
  FROM idb_hierarchical I  
 START WITH id =2  
CONNECT BY PARENT_ID = PRIOR ID;  
表4
STR_LEVEL    ID    PARENT_ID    LVL
+..B    2    1    1
+....C    3    2    2
+......D    4    3    3
+........H    8    4    4
+........I    9    4    4
+......G    7    3    3
+....E    5    2    2
+....F    6    2    2
根节点ID应该为3、5、6，即lvl为1即可

查询根节点，只显示根节点SQL

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SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       LEVEL LVL,  
       (select b.str  
          from idb_hierarchical b  
         where level = 1  
         start with b.id = 2  
        connect by prior b.id =  b.parent_id  
        ) root_str  
  FROM idb_hierarchical I  
 where level = 1  
 START WITH id = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       LEVEL LVL,  
       (select b.str  
          from idb_hierarchical b  
         where level = 1  
         start with b.id = 2  
        connect by prior b.id =  b.parent_id  
        ) root_str  
  FROM idb_hierarchical I  
 where level = 1  
 START WITH id = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
表5
STR_LEVEL    ID    PARENT_ID    LVL    ROOT_STR
+..B    2    1    1    B
标明根节点SQL

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SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       DECODE(LEVEL, 1, 'Y', 'N') is_root,  
       LEVEL LVL,  
       (select b.str  
          from idb_hierarchical b  
         where level = 1  
         start with b.id = 2  
        connect by prior b.id = b.parent_id) root_str  
  FROM idb_hierarchical I  
 START WITH id = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       DECODE(LEVEL, 1, 'Y', 'N') is_root,  
       LEVEL LVL,  
       (select b.str  
          from idb_hierarchical b  
         where level = 1  
         start with b.id = 2  
        connect by prior b.id = b.parent_id) root_str  
  FROM idb_hierarchical I  
 START WITH id = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
表6
STR_LEVEL    ID    PARENT_ID    IS_ROOT    LVL    ROOT_STR
+..B    2    1    Y    1    B
+....C    3    2    N    2    B
+......D    4    3    N    3    B
+........H    8    4    N    4    B
+........I    9    4    N    4    B
+......G    7    3    N    3    B
+....E    5    2    N    2    B
+....F    6    2    N    2    B
在oracle 10g提供了connect_by_isleaf和connect_by_root

oracle 10g用connect_by_isleaf判断叶节点
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SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL  
  FROM idb_hierarchical I  
where connect_by_isleaf=1  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL  
  FROM idb_hierarchical I  
where connect_by_isleaf=1  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
表7
STR_LEVEL    ID    PARENT_ID    LVL
+..........H    8    4    5
+..........I    9    4    5
+........G    7    3    4
+......E    5    2    3
+......F    6    2    3
+......L    12    11    3
+....M    13    10    2
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SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL,  
decode(connect_by_isleaf,1,'Y','N') IS_LEAF  
  FROM idb_hierarchical I  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+',LEVEL*2+1,'.')||STR STR_LEVEL,ID,PARENT_ID,LEVEL LVL,  
decode(connect_by_isleaf,1,'Y','N') IS_LEAF  
  FROM idb_hierarchical I  
 START WITH PARENT_ID IS NULL  
CONNECT BY PARENT_ID = PRIOR ID;  
表8
STR_LEVEL    ID    PARENT_ID    LVL    IS_LEAF
+..A    1         1    N
+....B    2    1    2    N
+......C    3    2    3    N
+........D    4    3    4    N
+..........H    8    4    5    Y
+..........I    9    4    5    Y
+........G    7    3    4    Y
+......E    5    2    3    Y
+......F    6    2    3    Y
+..J    10         1    N
+....K    11    10    2    N
+......L    12    11    3    Y
+....M    13    10    2    Y
oracle 10g用connect_by_root判断根节点
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SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       LEVEL LVL,  
       connect_by_root STR ROOT_STR  
  FROM idb_hierarchical I  
 START WITH id = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       LEVEL LVL,  
       connect_by_root STR ROOT_STR  
  FROM idb_hierarchical I  
 START WITH id = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
表9
STR_LEVEL    ID    PARENT_ID    LVL    ROOT_STR
+..B    2    1    1    B
+....C    3    2    2    B
+......D    4    3    3    B
+........H    8    4    4    B
+........I    9    4    4    B
+......G    7    3    3    B
+....E    5    2    2    B
+....F    6    2    2    B
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SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       DECODE(LEVEL, 1, 'Y', 'N') is_root,  
       LEVEL LVL,  
       connect_by_root STR ROOT_STR  
  FROM idb_hierarchical I  
 START WITH id = 3  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       DECODE(LEVEL, 1, 'Y', 'N') is_root,  
       LEVEL LVL,  
       connect_by_root STR ROOT_STR  
  FROM idb_hierarchical I  
 START WITH id = 3  
CONNECT BY PARENT_ID = PRIOR ID;  
表10
STR_LEVEL    ID    PARENT_ID    IS_ROOT    LVL    ROOT_STR
+..C    3    2    Y    1    C
+....D    4    3    N    2    C
+......H    8    4    N    3    C
+......I    9    4    N    3    C
+....G    7    3    N    2    C
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SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       DECODE(LEVEL, 1, 'Y', 'N') is_root,  
       LEVEL LVL,  
       connect_by_root STR ROOT_STR  
  FROM idb_hierarchical I  
 START WITH PARENT_ID = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
[sql] view plaincopy
SELECT RPAD('+', LEVEL * 2 + 1, '.') || STR STR_LEVEL,  
       ID,  
       PARENT_ID,  
       DECODE(LEVEL, 1, 'Y', 'N') is_root,  
       LEVEL LVL,  
       connect_by_root STR ROOT_STR  
  FROM idb_hierarchical I  
 START WITH PARENT_ID = 2  
CONNECT BY PARENT_ID = PRIOR ID;  
表11
STR_LEVEL    ID    PARENT_ID    IS_ROOT    LVL    ROOT_STR
+..C    3    2    Y    1    C
+....D    4    3    N    2    C
+......H    8    4    N    3    C
+......I    9    4    N    3    C
+....G    7    3    N    2    C
+..E    5    2    Y    1    E
+..F    6    2    Y    1    F