Recursive SETOF function

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.uid=@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 =@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=@cid)
END
END
RETURN
END

--


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Re: Recursive SETOF function

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
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.uid=@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 =@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=@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 =@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=@cid;
END LOOP;
RETURN
END;' LANGUAGE 'plpgsql';


Hope that helps!

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>


--
Mike Rylander
mrylander@gmail.com
GPLS -- PINES Development
Database Developer

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Re: Recursive SETOF function

Forgot one line. See below

On Mon, 22 Nov 2004 11:54:30 -0500, Mike Rylander wrote:
> I'm feeling sausey today, so here is my (untested) attempt to
[snip]
> > 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 =@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=@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 * FROM providers WHERE uid =@child_provider) > 0
IF NOT FOUND
RETURN;
END IF;

> LOOP
> cid := child_provider
> IF cid IS NULL THEN
> EXIT;
> END IF;
> RETURN NEXT cid;
> SELECT INTO cid parent_id FROM providers WHERE uid=@cid;
> END LOOP;
> RETURN
> END;' LANGUAGE 'plpgsql';
>
> Hope that helps!
>
> > --
>
>
> >
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> >
>
>
> --
> Mike Rylander
> mrylander@gmail.com
> GPLS -- PINES Development
> Database Developer
>


--
Mike Rylander
mrylander@gmail.com
GPLS -- PINES Development
Database Developer

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Re: Recursive SETOF function

I have been fiddling with what you sent. I have it working mostly, save
for I keep getting syntax errors on the "RETURN NEXT cid;" line. If I
remove this line then the function works ( but returns nothing of
course). Any ideas on why the RETURN NEXT doesn't like the variable as
a parameter?

sp_demo_505=# CREATE OR REPLACE FUNCTION svp_getparentproviderids
(INTEGER)
RETURNS SETOF svp_getparentproviderids_uid_type
AS '
DECLARE
child_provider ALIAS FOR $1;
cid INTEGER;
BEGIN
SELECT INTO cid count(*) FROM providers WHERE uid =child_provider;
IF cid = 0 THEN
RAISE EXCEPTION ''Inexistent ID --> %'', child_provider;
RETURN;
END IF;
cid := child_provider;
LOOP
EXIT WHEN cid IS NULL;
RETURN NEXT cid;
SELECT INTO cid parent_id FROM providers WHERE uid=cid;
END LOOP;
RETURN;
END;' LANGUAGE 'plpgsql';
CREATE FUNCTION
sp_demo_505=# select * from svp_getparentproviderids(21112);
ERROR: incorrect argument to RETURN NEXT at or near "cid"
CONTEXT: compile of PL/pgSQL function "svp_getparentproviderids" near
line 13



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Re: [postgres] Re: Recursive SETOF function

Sorry about that... try this:

CREATE OR REPLACE FUNCTION svp_getparentproviderids
(INTEGER)
RETURNS SETOF svp_getparentproviderids_uid_type
AS '
DECLARE
child_provider ALIAS FOR $1;
cid svp_getparentproviderids_uid_type%ROWTYPE;
tmp_cid INTEGER;
BEGIN
SELECT INTO tmp_cid count(*) FROM providers WHERE uid =child_provider;
IF tmp_cid = 0 THEN
RAISE EXCEPTION ''Inexistent ID --> %'', child_provider;
RETURN;
END IF;
cid.uid := child_provider;
LOOP
EXIT WHEN tmp_cid IS NULL;
RETURN NEXT cid;
SELECT INTO tmp_cid parent_id FROM providers WHERE uid=cid.uid;
END LOOP;
RETURN;
END;' LANGUAGE 'plpgsql';

On Mon, 22 Nov 2004 12:51:41 -0600, Richard Rowell
wrote:
> I have been fiddling with what you sent. I have it working mostly, save
> for I keep getting syntax errors on the "RETURN NEXT cid;" line. If I
> remove this line then the function works ( but returns nothing of
> course). Any ideas?
>
> sp_demo_505=# CREATE OR REPLACE FUNCTION svp_getparentproviderids
> (INTEGER)
> RETURNS SETOF svp_getparentproviderids_uid_type
> AS '
> DECLARE
> child_provider ALIAS FOR $1;
> cid INTEGER;
> BEGIN
> SELECT INTO cid count(*) FROM providers WHERE uid =child_provider;
> IF cid = 0 THEN
> RAISE EXCEPTION ''Inexistent ID --> %'', child_provider;
> RETURN;
> END IF;
> cid := child_provider;
> LOOP
> EXIT WHEN cid IS NULL;
> RETURN NEXT cid;
> SELECT INTO cid parent_id FROM providers WHERE uid=cid;
> END LOOP;
> RETURN;
> END;' LANGUAGE 'plpgsql';
> CREATE FUNCTION
> sp_demo_505=# select * from svp_getparentproviderids(21112);
> ERROR: incorrect argument to RETURN NEXT at or near "cid"
> CONTEXT: compile of PL/pgSQL function "svp_getparentproviderids" near
> line 13
>
>


--
Mike Rylander
mrylander@gmail.com
GPLS -- PINES Development
Database Developer

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Re: [postgres] Re: Recursive SETOF function

I had to fiddle a bit more, but I did finally get it to work. Thanks
Mike

CREATE OR REPLACE FUNCTION svp_getparentproviderids (INTEGER)
RETURNS SETOF INTEGER
AS '
DECLARE
child_provider ALIAS FOR $1;
cid INTEGER;
BEGIN
SELECT INTO cid count(*) FROM providers WHERE uid =child_provider;
IF cid = 0 THEN
RAISE EXCEPTION ''Inexistent ID --> %'', child_provider;
RETURN;
END IF;
cid := child_provider;
LOOP
EXIT WHEN cid IS NULL;
RAISE WARNING ''LOOP: Adding (%) to results'', cid;
RETURN NEXT cid;
SELECT INTO cid parent_id FROM providers WHERE uid=cid;
END LOOP;
RETURN;
END;' LANGUAGE 'plpgsql';


On Mon, 2004-11-22 at 14:39 -0500, Mike Rylander wrote:
> Sorry about that... try this:
>
> CREATE OR REPLACE FUNCTION svp_getparentproviderids
> (INTEGER)
> RETURNS SETOF svp_getparentproviderids_uid_type
> AS '
> DECLARE
> child_provider ALIAS FOR $1;
> cid svp_getparentproviderids_uid_type%ROWTYPE;
> tmp_cid INTEGER;
> BEGIN
> SELECT INTO tmp_cid count(*) FROM providers WHERE uid =child_provider;
> IF tmp_cid = 0 THEN
> RAISE EXCEPTION ''Inexistent ID --> %'', child_provider;
> RETURN;
> END IF;
> cid.uid := child_provider;
> LOOP
> EXIT WHEN tmp_cid IS NULL;
> RETURN NEXT cid;
> SELECT INTO tmp_cid parent_id FROM providers WHERE uid=cid.uid;
> END LOOP;
> RETURN;
> END;' LANGUAGE 'plpgsql';
>
> On Mon, 22 Nov 2004 12:51:41 -0600, Richard Rowell
> wrote:
> > I have been fiddling with what you sent. I have it working mostly, save
> > for I keep getting syntax errors on the "RETURN NEXT cid;" line. If I
> > remove this line then the function works ( but returns nothing of
> > course). Any ideas?
> >
> > sp_demo_505=# CREATE OR REPLACE FUNCTION svp_getparentproviderids
> > (INTEGER)
> > RETURNS SETOF svp_getparentproviderids_uid_type
> > AS '
> > DECLARE
> > child_provider ALIAS FOR $1;
> > cid INTEGER;
> > BEGIN
> > SELECT INTO cid count(*) FROM providers WHERE uid =child_provider;
> > IF cid = 0 THEN
> > RAISE EXCEPTION ''Inexistent ID --> %'', child_provider;
> > RETURN;
> > END IF;
> > cid := child_provider;
> > LOOP
> > EXIT WHEN cid IS NULL;
> > RETURN NEXT cid;
> > SELECT INTO cid parent_id FROM providers WHERE uid=cid;
> > END LOOP;
> > RETURN;
> > END;' LANGUAGE 'plpgsql';
> > CREATE FUNCTION
> > sp_demo_505=# select * from svp_getparentproviderids(21112);
> > ERROR: incorrect argument to RETURN NEXT at or near "cid"
> > CONTEXT: compile of PL/pgSQL function "svp_getparentproviderids" near
> > line 13
> >
> >
>
>
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Re: Recursive SETOF function

> SELECT INTO cid count(*) FROM providers WHERE uid =child_provider;

Hey, hey.
Better :

SELECT blablah FROM providers WHERE uid = child_provider LIMIT 1;
IF NOT FOUND THEN exit with error ELSE do your stuff

Why scan more than 1 row when you just need existence ?
Or :

SELECT INTO cid parent_id FROM providers WHERE uid=cid;
WHILE FOUND
RETURN NEXT cid;
SELECT INTO cid parent_id FROM providers WHERE uid=cid;
END;

Not sure about the While syntax but you get the idea.

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