Re: Recursion and SQL

[rob@xxxxxxxxx]

RPG does allow recursion via subprocedures.  Perhaps you could write a 
stored procedure in RPG that could return the desired result sets?

Rob Berendt
-- 
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





"Smith, Dave" <DSmith@xxxxxxxxx> 
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03/30/2005 09:47 AM
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Subject
Recursion and SQL






I am looking for a good example of breaking down a table that forms a
parent child relationship of unknown levels (Tree structure).

 

PARENT           CHILD

                        A

A                      B 

A                      C 

A                      D 

B                      E 

B                      F 

E                      G 

E                      J 

G                      K 

H                      L 

 

I saw some good examples of recursive SQL on the web but apparently
that's not allowed on the iSeries V5R2.   I believe in won't be allowed
under V5R3 but I can not find where I read that. 

 

I get the following message when trying a recursive SQL statement:
Message: [SQL0346] Recursion not allowed for common table expressions.

 

This is the result I'm looking for:

 

LEVEL              PARENT           CHILD 

1                      A                      B 

2                      B                      E 

3                      E                      G 

4                      G                      K 

3                      E                      J

2                      B                      F


1                      A                      C

1                      A                      D

1                      H                      L

 

I can then easily show this as:

LEVEL  1          2          3          4 

            A          B

                        B          E

                                    E          G

                                                G          K

                                    E          J

                        B          F

            A          C

            A          D

            H          L 

 

I want to do this for a warehousing application to show who feeds who.
I was able to union a bunch of SQL statements together to achieve the
desired results but it's ugly and does not account for unlimited levels.
I can do it using RPG or using a combination of RPG and embedded SQL.
Is there a simple SQL only solution that I'm missing?

 

David Smith

IT Consultant

 

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