用Oracle 10g新层次伪列探查层次循环

column "Reports To" format a30

set pagesize 9999



SELECT LPAD(' ', 2*(LEVEL-1))||last_name "Reports To", employee_id

FROM employees

START WITH employee_id IN (101, 102)

CONNECT BY PRIOR employee_id = manager_id

/



Reports To                     EMPLOYEE_ID                                      

------------------------------ -----------                                      

De Haan                                102                                      
  Hunold                               103                                      
    Austin                             105                                      
    Ernst                              104                                      
    Lorentz                            107                                      
    Pataballa                          106                                      
Kochhar                                101                                      
  Baer                                 204                                      
  Greenberg                            108                                      
    Chen                               110                                      
    Faviet                             109                                      
    Popp                               113                                      
    Sciarra                            111                                      
    Urman                              112                                      
      Kochhar                          101                                      

ERROR:

ORA-01436: CONNECT BY loop in user data