查询部门下的所有下级部门

with Dept as(
    select id,departmentname,supdepid from hrmdepartment  where id='19'
    union all
    select HrmDept.id,HrmDept.departmentname,HrmDept.supdepid from hrmdepartment HrmDept,Dept  
    -- 当前部门所有下级  
    where HrmDept.supdepid=Dept.id
    -- 当前部门所有上级 where T.supdepid=D.id
)
select * from Dept