connect by Nocycle Prior

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

第一句只能查询出父节点是BRA0000000000001的所有子节点

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

这一句能查出父节点是BRA0000000000001的所有子节点，然后它的子节点的子节点都能查出来

语法：

[ 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;

小结：

测试时，不指定start with会出现重复记录，反而不指定NOCYCLE却没事