postgresql中实现oracle SYS_CONNECT_BY_PATH

oracle:

select sys_connect_by_path(t2.ID, '/') as PATH, t1.id 
            from HTD_DEVICETYPE_RELATION t1
            inner join HTD_DEVICETYPE_RESOURCE t2 on t1.CHILD_RESOURCE_TYPE_ID = t2.ID
            start with t1.parent_resource_type_id = 100 and t1.id > 1 connect by nocycle
      prior t2.id = t1.parent_resource_type_id order by t1.id

postgresql:

with recursive r_table(path,cycle,t1id,t2id,parent_resource_type_id) as
(
     select array[t.t2id],false,t.t1id,t.t2id,parent_resource_type_id from
     
     (select t1.id as t1id,t2.id as t2id,t1.parent_resource_type_id as parent_resource_type_id
     from HTD_DEVICETYPE_RELATION as t1
     inner join HTD_DEVICETYPE_RESOURCE as t2 on
     t1.CHILD_RESOURCE_TYPE_ID = t2.ID where t1.parent_resource_type_id = 100 and t1.id > 1) as t
     
     union all
     select path || b.t2id,b.t2id = any(path),b.t1id,b.t2id,b.parent_resource_type_id
     from r_table
     inner join
     (select t1.id as t1id,t2.id as t2id,t1.parent_resource_type_id as parent_resource_type_id
     from HTD_DEVICETYPE_RELATION as t1
     inner join HTD_DEVICETYPE_RESOURCE as t2 on
     t1.CHILD_RESOURCE_TYPE_ID = t2.ID) as b
     
     on r_table.t2id = b.parent_resource_type_id and not cycle
)select '/' || Array_to_string(path,'/'),t1id from r_table where not cycle order by t1id;

         ?column?         | t1id
--------------------------+------
 /31                      |    9
 /31/32                   |   10
 /102                     | 1519
 /103                     | 1520
 /104                     | 1521
 /105                     | 1522
 /102/115                 | 1523
 /102/160                 | 1524
 /102/103/115             | 1526
 /103/115                 | 1526
 /103/160                 | 1527
 /102/103/160             | 1527
 /102/103/113             | 1528
 /103/113                 | 1528
 /104/160                 | 1530
 /102/104/160             | 1530
 /102/105/115             | 1531
 /105/115                 | 1531
 /102/105/160             | 1532
 /105/160                 | 1532
 /102/105/113             | 1533
 /105/113                 | 1533
 /484                     | 1534
 /491                     | 1554
 /102/104/114             | 1556
 /104/114                 | 1556
 /185                     | 1596
 /154                     | 1614
 /493                     | 1634
 /504                     | 1635
--More--

实例中通过array数值保存访问过的id,b.t2id = any(path)检查是否已经访问过来避免产生死循环

在递归查询时,如出现如下错误

是由于数据库表字段类型numeric(20,0)不支持with递归查询,将数据库表字段改为bigint即可。

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原文地址:https://www.cnblogs.com/mxly/p/9458569.html