PostgreSQL 对简单树的遍历

标签：postgresql   遍历   递归   oracle   path   

t_girl=# with recursive tmp_country(id,path) as 
t_girl-# (
t_girl(# select a.id,‘/‘||b.name as "path" from country_relation as a  inner join country as b on (a.id = b.id) where a.parentid is null
t_girl(# union all
t_girl(# select a.id,q.path||‘/‘||b.name  as "path" from country_relation as a inner join tmp_country as q on (q.id = a.parentid)
t_girl(# inner join country as b on (a.id = b.id)
t_girl(# )
t_girl-# select a.path from tmp_country as a;
                     path                      
-----------------------------------------------
 /Earth
 /Earth/North America
 /Earth/South America
 /Earth/Europe
 /Earth/Asia
 /Earth/Africa
 /Earth/Australia
 /Earth/North America/Canada
 /Earth/North America/Central America
 /Earth/North America/Island Nations
 /Earth/North America/United States
 /Earth/North America/United States/Alabama
 /Earth/North America/United States/Alaska
 /Earth/North America/United States/Arizona
 /Earth/North America/United States/Arkansas
 /Earth/North America/United States/California
(16 rows)


Time: 3.260 ms

t_girl=# CREATE TEMPORARY TABLE tmp_country_relation  as SELECT b.id,a.name,b.parentid,‘‘::text as parentname FROM country AS a,country_relation AS b WHERE a.id = b.id;      
SELECT 16
Time: 11.773 ms
t_girl=# 

t_girl=# update tmp_country_relation set parentname = a.name from country as a where parentid = a.id;
UPDATE 15
Time: 1.829 ms

t_girl=# select path from connectby(‘tmp_country_relation as a‘,‘a.name‘,‘a.parentname‘,‘Earth‘,0,‘/‘) as g(id text,parentid text,level int,path text) order by level;   
                     path                     
----------------------------------------------
 Earth
 Earth/Australia
 Earth/North America
 Earth/Africa
 Earth/South America
 Earth/Europe
 Earth/Asia
 Earth/North America/Island Nations
 Earth/North America/Canada
 Earth/North America/Central America
 Earth/North America/United States
 Earth/North America/United States/California
 Earth/North America/United States/Arkansas
 Earth/North America/United States/Alabama
 Earth/North America/United States/Alaska
 Earth/North America/United States/Arizona
(16 rows)


Time: 5.974 ms
t_girl=# 

PostgreSQL 对简单树的遍历

标签：postgresql   遍历   递归   oracle   path   

原文地址：http://blog.csdn.net/yueliangdao0608/article/details/40821235