DEPTH가 결과값이라고 보면 됨.
쿼리1) DEPTH가 2단계
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 2;
쿼리1-결과) - 2개의 값이 나옴
--------------------------------------
1
2
--------------------------------------
쿼리2)
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 3;
쿼리2-결과)
--------------------------------------
1
2
3
--------------------------------------
궈리3) TREE의 갯수가 1이고 DEPTH가 2단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 1
)
CONNECT BY LEVEL <= 2;
쿼리3-결과)
--------------------------------------
1
2
--------------------------------------
쿼리4)TREE의 갯수가 1이고 DEPTH가 3단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 1
)
CONNECT BY LEVEL <= 3;
쿼리4-결과)
--------------------------------------
1
2
3
--------------------------------------
쿼리5)TREE의 갯수가 2이고 DEPTH가 1단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 2
)
CONNECT BY LEVEL <= 1;
쿼리5-결과)
--------------------------------------
1
1
--------------------------------------
쿼리6) TREE의 갯수가 3이고 DEPTH가 1단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 3
)
CONNECT BY LEVEL <= 1;
쿼리6-결과)
--------------------------------------
1
1
1
--------------------------------------
쿼리7) TREE의 갯수가 2이고 DEPTH가 2단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 2
)
CONNECT BY LEVEL <= 2;
쿼리7-결과)
--------------------------------------
1
2
2
1
2
2
--------------------------------------
쿼리8) TREE의 갯수가 2이고 DEPTH가 3단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 2
)
CONNECT BY LEVEL <= 3;
쿼리8-결과)
--------------------------------------
1
2
3
3
2
3
3
1
2
3
3
2
3
3
--------------------------------------
쿼리9)TREE의 갯수가 2이고 DEPTH가 4단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 2
)
CONNECT BY LEVEL <= 4;
쿼리9-결과)
--------------------------------------
1
2
3
4
4
3
4
4
2
3
4
4
3
4
4
1
2
3
4
4
3
4
4
2
3
4
4
3
4
4
--------------------------------------
쿼리11) TREE의 갯수가 3이고 DEPTH가 2단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 3
)
CONNECT BY LEVEL <= 2;
쿼리11-결과)
--------------------------------------
1
2
2
2
1
2
2
2
1
2
2
2
--------------------------------------
쿼리12)TREE의 갯수가 4이고 DEPTH가 2단계
SELECT LEVEL
FROM (
SELECT LEVEL
FROM DUAL
CONNECT BY LEVEL <= 4
)
CONNECT BY LEVEL <= 2;
쿼리12-결과)
--------------------------------------
1
2
2
2
2
1
2
2
2
2
1
2
2
2
2
1
2
2
2
2
--------------------------------------
참고)
http://donatm.blog.me/20133117593
http://blog.naver.com/ooabc/20207191941
