Oracle 的递归查询将层级变成字符串

select A.PARENT_GROUP_ID, A.GROUP_ID,sys_connect_by_path(A.GROUP_ID,'/') || '/' path
from dam_dataentry_group A
START WITH A.GROUP_ID in (select well_id from md_well)
CONNECT BY PRIOR A.GROUP_ID = A.PARENT_GROUP_ID

使用到系统自带的函数：sys_connect_by_path