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Editorial Team
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Asked: 2026-05-30T22:40:48+00:00

Oracle ships with a very handy feature. You can create hierarchical queries (recursive behaviour)

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Oracle ships with a very handy feature. You can create hierarchical queries (recursive behaviour) using the following clause:

CONNECT BY [NOCYCLE] {condition [AND condition...]} [START WITH condition]

As documented here:

http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/queries003.htm

I’m wondering, are there any other established RDBMS that support an equivalent or similar syntax? Or can recursive behaviour like this be generically simulated using regular SQL?

A good example that I’d like to be able to simulate is this (taken from the Oracle documentation):

    SELECT LPAD(' ', 2 * (LEVEL-1)) || last_name org_chart, 
           employee_id, manager_id, job_id
      FROM employees
START WITH job_id = 'AD_VP' 
CONNECT BY PRIOR employee_id = manager_id;

Resulting in:

ORG_CHART          EMPLOYEE_ID MANAGER_ID JOB_ID
------------------ ----------- ---------- ----------
Kochhar                    101        100 AD_VP
  Greenberg                108        101 FI_MGR
    Faviet                 109        108 FI_ACCOUNT
    Chen                   110        108 FI_ACCOUNT
    Sciarra                111        108 FI_ACCOUNT
    Urman                  112        108 FI_ACCOUNT
    Popp                   113        108 FI_ACCOUNT
  Whalen                   200        101 AD_ASST
  Mavris                   203        101 HR_REP
  Baer                     204        101 PR_REP
  Higgins                  205        101 AC_MGR
    Gietz                  206        205 AC_ACCOUNT
De Haan                    102        100 AD_VP
  Hunold                   103        102 IT_PROG
    Ernst                  104        103 IT_PROG
    Austin                 105        103 IT_PROG
    Pataballa              106        103 IT_PROG
    Lorentz                107        103 IT_PROG

The LEVEL pseudo column and the indentation achieved with it is not so important to me

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1 Answer

  1. Editorial Team

    There is an article on the developerworks site Port CONNECT BY to DB2 that does a nice conversion.
    Also an interesting article on Explain Extended (Quassnoi’s blog) that shows some difference between CONNECT BY and recursive CTE: Adjacency list vs. nested sets: Oracle, being row-based and set-based. He has also a nice article about “SQL Server: are the recursive CTE’s really set-based?”. It seems that the “recursive CTE in Oracle is also not set based”. I hope this helps with the conversion, recursion in JOOQ and understanding the difference of both implementations of recursion in SQL.

    Regards,
    JJ.

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