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Re: Recursive SETOF function

From: Mike Rylander <mrylander(at)gmail(dot)com>
To: Richard Rowell <richard(at)bowmansystems(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: Recursive SETOF function
Date: 2004-11-22 16:54:30
Message-ID: b918cf3d041122085437cde2f1@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-sql
I'm feeling sausey today, so here is my (untested) attempt to
translate your function.  It's inline below, and you'll want to look
here http://www.postgresql.org/docs/7.4/interactive/plpgsql.html for
more information.

On Mon, 22 Nov 2004 09:18:13 -0600, Richard Rowell
<richard(at)bowmansystems(dot)com> wrote:
> I'm trying to port some TSQL to PLPGSQL.  The DB has a table with a
> recursive foreign key that represents a tree hierarchy.  I'm trying to
> re-create a TSQL function that pulls out all the ancestors of a given
> node in the hierarchy.
> 
> I'm rather new to PLSQL and I have several questions.
> 
> 1.  In TSQL, I can assign a scalar to the result of query like so:
>   SET @var1 = (SELECT foo FROM bar WHERE bar(dot)uid=(at)var2)
> 
> How would I do this in PLSQL?
> 
> 2.  In TSQL the "result table" can be inserted into manually.  IE:
> 
> CREATE FUNCTION foo () RETURNS @ttable TABLE( uid INTEGER) AS BEGIN
>         INSERT @ttable VALUES (1)
>         RETURN
> END
> 
> Is there a way to manually insert rows into the result table in PLSQL?
> 
> What follows is my TSQL function if that helps give context.
> 
> CREATE FUNCTION svp_getparentproviderids (@child_provider INTEGER)
> RETURNS @provider_ids TABLE ( uid INTEGER )
> AS
> BEGIN
>     DECLARE @cid AS INTEGER
>     IF (SELECT count(*) FROM providers WHERE uid =(at)child_provider) > 0
>     BEGIN
>         SET @cid = @child_provider
>         WHILE @cid IS NOT NULL
>         BEGIN
>             INSERT @provider_ids VALUES (@cid)
>             SET @cid = (SELECT parent_id FROM providers WHERE uid=(at)cid)
>         END
>     END
>     RETURN
> END
> 

-- This TYPE will get you a named column... easier to use SRFs with a
preexisting type.
CREATE TYPE svp_getparentproviderids_uid_type AS ( uid INTEGER );

CREATE FUNCTION svp_getparentproviderids (INTEGER)
   RETURNS SETOF svp_getparentproviderids_uid_type
   AS '
DECLARE
  child_provider ALIAS FOR $1;
  cid INTEGER;
BEGIN
    SELECT count(*) FROM providers WHERE uid =(at)child_provider) > 0
    LOOP
        cid := child_provider
        IF cid IS NULL THEN
          EXIT;
        END IF;
        RETURN NEXT cid;
        SELECT INTO cid parent_id FROM providers WHERE uid=(at)cid;
    END LOOP;
    RETURN
END;' LANGUAGE 'plpgsql';


Hope that helps!

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-- 
Mike Rylander
mrylander(at)gmail(dot)com
GPLS -- PINES Development
Database Developer

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Subject: Re: Recursive SETOF function
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Subject: Missing SELECT INTO ... DEFAULT VALUES in plpgsql for composite types

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