标签：style blog http io ar os sp 数据 on
SELECT ... FROM <TABLENAME> WHERE <CONDITIONAL-1> START WITH <CONDITIONAL-2> CONNECT BY <CONDITIONAL-3>
2.CONDITIONAL-2条件：是根结点的限定语句；是从哪个条件开始。
至于它们的作用；我们用下面一个例句来理解
SQL> select * from li0924;
ROOT_ID ID NAME
---------- ---------- ----------
0 1 namei --最近在看海贼王；借用下名字
1 2 lufei
1 3 shanzhi
0 4 qiaoba
3 5 suolong
4 6 luobin
6 rows selected.
SQL> SELECT root_id,PRIOR ID,ID,NAME,LEVEL FROM i0924
2 START WITH root_id = 0
3 CONNECT BY root_id = PRIOR ID; --注意root_id和prior id这两列。其中level可以看作是深度
ROOT_ID PRIORID ID NAME LEVEL
---------- ---------- ---------- ---------- ----------
0 1 namei 1
1 1 2 lufei 2
1 1 3 shanzhi 2
3 3 5 suolong 3
0 4 qiaoba 1
4 4 6 luobin 2
6 rows selected.
作用：
SQL> SELECT LEVEL FROM dual CONNECT BY LEVEL <= 10;
LEVEL
----------
1
2
3
4
5
6
7
8
9
10
10 rows selected.
【2】分割字符串
SELECT CONNECT_BY_ROOT NAME "ROOT" , 2 CONNECT_BY_ISLEAF "ISLEAF", 3 SYS_CONNECT_BY_PATH(NAME, ‘/‘) AS PATH 4 FROM li0924 5 START WITH root_id = 0 6 CONNECT BY root_id = PRIOR ID; ROOT ISLEAF PATH -------------------------------------------------------------------------------- namei 0 /namei namei 1 /namei/lufei namei 0 /namei/shanzhi namei 1 /namei/shanzhi/suolong qiaoba 0 /qiaoba qiaoba 1 /qiaoba/luobin 6 rows selected.
说说这CONNECT_BY_ROOT，CONNECT_BY_ISLEAF，SYS_CONNECT_BY_PATH，这三个函数的意义
CONNECT_BY_ROOT: 返回当前节点的最顶端节点 CONNECT_BY_ISLEAF: 判断是否为叶子节点，如果有则返回0；没有返回1 SYS_CONNECT_BY_PATH:函数显示详细路径，并用“/”分隔.其中这个分隔符可以替换。
作者 ： li0924
时间 ： 2014-11-20
本文版权归作者所有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接.
标签：style blog http io ar os sp 数据 on
原文地址：http://www.cnblogs.com/lottu/p/4111236.html
