Oracle Connect by与递归with

层次查询

select
*
from emp;

select empno,

ename,

job,

mgr,

sal,

deptno,level lv,

sys_connect_by_path(ename,
'->') tree_path,

connect_by_root(ename) tree_root,

connect_by_isleaf isleaf,

decode(connect_by_isleaf,1,ename,null) tree_leaf

from emp

start
with empno =
7369

connect
by
prior mgr = empno

order
by
level,empno;

with t(empno,

ename,

job,

mgr,

sal,

deptno,

lv,

tree_path,

tree_root,

isleaf,tree_leaf)
as

(select empno,

ename,

job,

mgr,

sal,

deptno,

1 lv,

'->'||ename,

ename,

(select
decode(count(1),
0,
1)
from emp where a.mgr = empno) isleaf,

(select
decode(count(1),
0, a.ename)
from emp where a.mgr = empno) leafname

from emp a

where empno =
'7369'

union
all

select a.empno,

a.ename,

a.job,

a.mgr,

a.sal,

a.deptno,

b.lv +
1,

b.tree_path ||
'->'
|| a.ename,

b.tree_root,

(select
decode(count(1),
0,
1)
from emp where a.mgr = empno) isleaf,

(select
decode(count(1),
0,a.ename)
from emp where a.mgr = empno) leafname

from emp a, t b

where a.empno = b.mgr)

select
*
from t order
by lv,empno;