[SQL]-(092) 계층형 질의문으로 서열을 주고 데이터 출력하기4

---

[Reference] 초보자를 위한 SQL 200제

---

[SQL 문법]

서열 순서를 가로로 출력할 수 있다.

SELECT ename,SYS_CONNECT_BY_PATH(ename, '/') as path
  FROM emp
  START WITH ename='KING'
  CONNECT BY prior empno = mgr 

[예시]

# 오라클 연동 및 접속
import pandas as pd
import cx_Oracle
dsn=cx_Oracle.makedsn('localhost',1521,'orcl')
db=cx_Oracle.connect('scott','tiger')
cursor=db.cursor()

# SQL 문법
cursor.execute("""
SELECT ename,SYS_CONNECT_BY_PATH(ename, '/') as path
  FROM emp
  START WITH ename='KING'
  CONNECT BY prior empno = mgr 
"""
)

row=cursor.fetchall()
colname=cursor.description
col=[]

for i in colname:
    col.append(i[0])

# pandas를 사용한 데이터 프레임 형식으로 변환
emp=pd.DataFrame(row,columns=col)
print(emp)

[결과]

     ENAME                    PATH
0     KING                   /KING
1    JONES             /KING/JONES
2     FORD        /KING/JONES/FORD
3    SMITH  /KING/JONES/FORD/SMITH
4    BLAKE             /KING/BLAKE
5    ALLEN       /KING/BLAKE/ALLEN
6     WARD        /KING/BLAKE/WARD
7   MARTIN      /KING/BLAKE/MARTIN
8   TURNER      /KING/BLAKE/TURNER
9    JAMES       /KING/BLAKE/JAMES
10   CLARK             /KING/CLARK
11  MILLER      /KING/CLARK/MILLER