Detailed Explanation of oracle SQL Recursion

If you need to use SQL recursive statement in oracle database, how should you write it? The following is an example of using SQL recursive statement in oracle for your reference.
Examples:

pid  id
  a   b   
  a   c     
  a   e   
  b   b1   
  b   b2   
  c   c1   
  e   e1   
  e   e3   
  d   d1   

 Specify pid=a , elected    
  a   b   
  a   c     
  a   e   
  b   b1   
  b   b2   
  c   c1   
  e   e1   
  e   e3  
SQL Statement: select   parent,child   from   test   start   with   pid='a'   
connect   by   prior   id=pid 

Oracle SQL Recursive Query Statement:
1. Table mechanism

SQL> desc comm_org_subjection
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------
 ORG_SUBJECTION_ID                         NOT NULL VARCHAR2(32)    Subkey 
 ORG_ID                                    NOT NULL VARCHAR2(32)
 FATHER_ORG_ID                             NOT NULL VARCHAR2(32)    Parent key 
 LOCKED_IF                                 NOT NULL VARCHAR2(1)
 START_DATE                                NOT NULL DATE
 END_DATE                                           DATE
 EDITION_NAMEPLATE                                  NUMBER(8)
 CODE_AFFORD_IF                                     VARCHAR2(1)
 CODE_AFFORD_ORG_ID                        NOT NULL VARCHAR2(32)
 CODING_SHOW_ID                                     NUMBER(8)
 BSFLAG                                             VARCHAR2(1)
 MODIFI_DATE                                        DATE
 CREATOR_ID                                         VARCHAR2(32)
 CREATE_DATE                                        DATE
 CREATOR                                            VARCHAR2(35)

2. Recursively find all child nodes under the parent node org_id as C60000000001:

select * from comm_org_subjection a
start with a.org_id='C6000000000001'
connect by prior a.org_subjection_id=a.father_org_id

3. Recursively find the child node org_id for all parent nodes under C6000000000001:

select org_id from comm_org_subjection a
start with a.org_id='C6000000000001'
connect by prior a.father_org_id=a.org_subjection_id