connect by Nocycle Prior

select branchid from branch where parentbranchid='BRA0000000000001' order by branchid

第一句只能查詢出父節點是BRA0000000000001的所有子節點

select br.branchid
  from Branch br
 start with br.branchid = 'BRA0000000000001'
connect by Nocycle Prior br.branchid = br.parentbranchid

這一句能查出父節點是BRA0000000000001的所有子節點，然后它的子節點的子節點都能查出來

語法：

[ START WITH condition ]
CONNECT BY [ NOCYCLE ] condition

 select abbrname,branchid,A.PARENTBRANCHID,branchtype,branchstatus,LEVEL from branch a
where a.branchstatus='BRANCHSTATUS_1'
AND a.branchtype='BRANCHTYPE_30'
start with a.branchid='BRA0000000000002'
connect by nocycle prior a.branchid = a.parentbranchid;

小結：

測試時，不指定start with會出現重復記錄，反而不指定NOCYCLE卻沒事