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List:       postgresql-sql
Subject:    Re: [SQL] plpgsql recursion
From:       Rod Taylor <rbt () rbt ! ca>
Date:       2003-05-23 1:59:43
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>       IF t_rec.node = testing THEN
>         RETURN ''Circular'';
>       ELSE
>         PERFORM dba_test(t_rec.node,testing);
>       END IF;
> I would use this function BEFORE inserting the new row. But if i try SELECT
> dba_test(4,1); i don't have the result i expect. Can i you give me an hint
> where am i wrong?

It's probably working as it's written :)  Once it finds 'Curcular' and
returns it to the recursed call of dba_test, you immediately throw away
the return value.

PERFORM should probably be replaced with:

ELSE
  -- ret is a variable
  SELECT dba_test(t_rec.node, testing) INTO ret;

  IF ret = ''Circular'' THEN
    RETURN ret;
  END IF;
END IF;


More to the point, if you're attempting to prevent circular items, and
this function will be used in the form of a trigger, then simply RAISE
EXCEPTION.  This way you can ignore having to deal with returned values.


-- 
Rod Taylor <rbt@rbt.ca>

PGP Key: http://www.rbt.ca/rbtpub.asc

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