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;