【Oracle】树状结构查询


【Oracle】树状结构查询
 
[sql] 
--oracle中的树状结构查询实际上就是一个中序遍历  
--显示以KING为根节点的树，start with定义起始节点  
SELECT *  
FROM   emp a  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--置于等号前面，由父节点向子节点方向检索；置于等号后面，则从子节点向父节点方向检索    
SELECT *  
FROM   emp a  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--使用伪列level来显示层级关系  
SELECT *  
FROM   emp a  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
  
SELECT level, a.*  
FROM   emp a  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--使用函数 sys_connect_by_path 显示全路径  
SELECT LEVEL, sys_connect_by_path(a.ename, '/'), a.*  
FROM   emp a  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--where子句只限定单个节点，不影响子其子节点或者父节点  
SELECT LEVEL, sys_connect_by_path(a.ename, '/'), a.*  
FROM   emp a  
WHERE a.empno <> 7369  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--connect by 子句限定整个以当前节点为起始节点的整个分支  
--connect_by_root 可以在列之前显示最高节点的内容  
SELECT LEVEL, connect_by_root(a.job),sys_connect_by_path(a.ename, '/'), a.*  
FROM   emp a  
WHERE a.empno <> 7369  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--connect_by_isleaf 显示当前行是否叶子节点，1：是；0：否  
SELECT LEVEL, connect_by_isleaf,sys_connect_by_path(a.ename, '/'), a.*  
FROM   emp a  
WHERE a.empno <> 7369  
START  WITH a.empno = 7839  
CONNECT BY PRIOR a.empno = a.mgr;  
--connect_by_iscycle 10g中开始有的新特性，用来判断当前节点是否产生了循环，0：否；1：是  
SELECT LEVEL, connect_by_iscycle, connect_by_isleaf,sys_connect_by_path(a.ename, '/'), a.*  
FROM   emp a  
WHERE a.empno <> 7369  
START  WITH a.empno = 7839  
CONNECT BY NOCYCLE PRIOR a.empno = a.mgr;