从同一个表的子父关系中选择数据

Question

我有以下表格架构：

create table location_master (id serial,name character varying,parent_id integer);

INSERT INTO location_master (name,parent_id)
VALUES
   ('Bombay',1)
 , ('Ahmedabad',1)
 , ('Surat',1)
 , ('Vapi',3)
 , ('Navarangpura',2);

从上表中我想找到从源id = 1到目的地id = 4的路径。所以预期的结果如下：

目的地id = 4。哪个有parent_id = 3。单词id = 3上有parent_id = 1等等。

例：
用户希望将包裹从id = 1发送到id = 4。宗地的路由路径由此表决定。当用户选择源id = 1和目标id = 4时，查询会自动从子父关系中找到路由。包裹将通过1,3,4路径。

我为此尝试了SELF JOIN，但没有得到预期的结果。

Answer 1

Thanks joop. I search for Recursive Query and got the solution as I want:

    WITH RECURSIVE demo AS (
    SELECT parent_id      
    FROM location_master                   
    WHERE id = <destination_id>
    UNION ALL
    SELECT a.parent_id               
    FROM location_master a                 
    JOIN demo b ON(a.id = b.parent_id))
    SELECT DISTINCT location_master.* FROM location_master JOIN demo 
           on location_master.id = demo.parent_id WHERE demo.parent_id != 0 
    UNION 
    SELECT location_master.* FROM location_master WHERE id = <destination_id> 
    ORDER BY id  ;