recursive function

Started by Karen Springeralmost 19 years ago6 messagesgeneral

karen.springer@wulfsberg.com

almost 19 years ago

Hi,

I am struggling to write my first recursive function and think I'm
missing something basic. I have written 2 functions that work if I pass
over one parameter, but if I try to pass over a series of parameters say
in a view for every field in the table it seems to run but never
displays data.

I have a table of built units.

tbl_BuiltAssemblies
ParentBarCode varchar(12)
ChildBarCode varchar(12)

I need to find the end ParentBarCode (Top Level) for each child. So if
I have

Parent Child
1 2
2 3
2 4
3 5

If I feed the function child 5, 4, 3, or 2, I need to get parent 1.
Since these are built units, each child can only be in one parent.

So far I've written this function which works great when passing over
one parameter.

CREATE OR REPLACE FUNCTION
"Production_Tracking"."GetTopLevelParent_WithView"(varchar)
RETURNS TEXT AS '

DECLARE
childBarCode ALIAS FOR $1;
parentBarCode TEXT;
topLevelParentBarCode TEXT;
BEGIN

SELECT INTO parentBarCode
"tbl_BuiltAssemblies"."ParentBarCode"
FROM "Production_Tracking"."tbl_BuiltAssemblies"
WHERE "tbl_BuiltAssemblies"."ChildBarCode" = childBarCode;

topLevelParentBarCode = parentBarCode;

WHILE FOUND LOOP
SELECT INTO parentBarCode
"tbl_BuiltAssemblies"."ParentBarCode"
FROM "Production_Tracking"."tbl_BuiltAssemblies"
WHERE "tbl_BuiltAssemblies"."ChildBarCode" = parentBarCode;
IF NOT(parentBarCode IS NULL) THEN
topLevelParentBarCode = parentBarCode;
END IF;
END LOOP;

RETURN (topLevelParentBarCode)::TEXT;

END;
' LANGUAGE 'plpgsql';

I have also written this too which again works great if I pass over one
parameter. (I would add a Level field to this & get the max level
eventually, but I don't want to spend more time on it until I know I'm
on the right track.)

CREATE OR REPLACE FUNCTION
"Production_Tracking"."GetTopLevelParent_WithView_1"(varchar)
RETURNS SETOF "Production_Tracking".cattree AS'

DECLARE
childbarcode ALIAS FOR $1;
parentbarcode "Production_Tracking".cattree%ROWTYPE;
toplevelparentbarcode "Production_Tracking".cattree%ROWTYPE;
BEGIN

FOR parentbarcode IN SELECT "ParentBarCode", childbarcode AS
"InitialChild"
FROM "Production_Tracking"."tbl_BuiltAssemblies" WHERE
"tbl_BuiltAssemblies"."ChildBarCode" = childbarcode LOOP

RETURN NEXT parentbarcode;

FOR toplevelparentbarcode IN SELECT "ParentBarCode",
childbarcode AS "InitialChild"
FROM
"Production_Tracking"."GetTopLevelParent_WithView_1"(parentbarcode."ParentBarCode")
LOOP

RETURN NEXT toplevelparentbarcode;

END LOOP;

RETURN;

END;
' LANGUAGE 'plpgsql';

Here are examples of the views I've tried

SELECT "tbl_BuiltAssemblies"."ChildBarCode",

"Production_Tracking"."GetTopLevelParent_WithView"("tbl_BuiltAssemblies"."ChildBarCode")
AS "TopLevelParent"
FROM "Production_Tracking"."tbl_BuiltAssemblies";

and

SELECT "tbl_BuiltAssemblies"."ChildBarCode",

"Production_Tracking"."GetTopLevelParent_WithView_1"("tbl_BuiltAssemblies"."ChildBarCode")
AS parents
FROM "Production_Tracking"."tbl_BuiltAssemblies";

These views seem to run, but never display data.

Any help would be most appreciated.

Thanks,
Karen

Pavel Stehule

pavel.stehule@gmail.com

almost 19 years ago

In reply to: Karen Springer (#1)

Re: recursive function

Hello

please, look on
http://people.planetpostgresql.org/merlin/index.php?/archives/2-Dealing-With-Recursive-Sets-With-PLPGSQL.html

Regards
Pavel Stehule

2007/6/13, Karen Springer <karen.springer@wulfsberg.com>:

Show quoted text

Hi,

I am struggling to write my first recursive function and think I'm
missing something basic. I have written 2 functions that work if I pass
over one parameter, but if I try to pass over a series of parameters say
in a view for every field in the table it seems to run but never
displays data.

I have a table of built units.

tbl_BuiltAssemblies
ParentBarCode varchar(12)
ChildBarCode varchar(12)

I need to find the end ParentBarCode (Top Level) for each child. So if
I have

Parent Child
1 2
2 3
2 4
3 5

If I feed the function child 5, 4, 3, or 2, I need to get parent 1.
Since these are built units, each child can only be in one parent.

So far I've written this function which works great when passing over
one parameter.

CREATE OR REPLACE FUNCTION
"Production_Tracking"."GetTopLevelParent_WithView"(varchar)
RETURNS TEXT AS '

DECLARE
childBarCode ALIAS FOR $1;
parentBarCode TEXT;
topLevelParentBarCode TEXT;
BEGIN

SELECT INTO parentBarCode
"tbl_BuiltAssemblies"."ParentBarCode"
FROM "Production_Tracking"."tbl_BuiltAssemblies"
WHERE "tbl_BuiltAssemblies"."ChildBarCode" = childBarCode;

topLevelParentBarCode = parentBarCode;

WHILE FOUND LOOP
SELECT INTO parentBarCode
"tbl_BuiltAssemblies"."ParentBarCode"
FROM "Production_Tracking"."tbl_BuiltAssemblies"
WHERE "tbl_BuiltAssemblies"."ChildBarCode" = parentBarCode;
IF NOT(parentBarCode IS NULL) THEN
topLevelParentBarCode = parentBarCode;
END IF;
END LOOP;

RETURN (topLevelParentBarCode)::TEXT;

END;
' LANGUAGE 'plpgsql';

I have also written this too which again works great if I pass over one
parameter. (I would add a Level field to this & get the max level
eventually, but I don't want to spend more time on it until I know I'm
on the right track.)

CREATE OR REPLACE FUNCTION
"Production_Tracking"."GetTopLevelParent_WithView_1"(varchar)
RETURNS SETOF "Production_Tracking".cattree AS'

DECLARE
childbarcode ALIAS FOR $1;
parentbarcode "Production_Tracking".cattree%ROWTYPE;
toplevelparentbarcode "Production_Tracking".cattree%ROWTYPE;
BEGIN

FOR parentbarcode IN SELECT "ParentBarCode", childbarcode AS
"InitialChild"
FROM "Production_Tracking"."tbl_BuiltAssemblies" WHERE
"tbl_BuiltAssemblies"."ChildBarCode" = childbarcode LOOP

RETURN NEXT parentbarcode;

FOR toplevelparentbarcode IN SELECT "ParentBarCode",
childbarcode AS "InitialChild"
FROM
"Production_Tracking"."GetTopLevelParent_WithView_1"(parentbarcode."ParentBarCode")
LOOP

RETURN NEXT toplevelparentbarcode;

END LOOP;

END LOOP;

RETURN;

END;
' LANGUAGE 'plpgsql';

Here are examples of the views I've tried

SELECT "tbl_BuiltAssemblies"."ChildBarCode",

"Production_Tracking"."GetTopLevelParent_WithView"("tbl_BuiltAssemblies"."ChildBarCode")
AS "TopLevelParent"
FROM "Production_Tracking"."tbl_BuiltAssemblies";

and

SELECT "tbl_BuiltAssemblies"."ChildBarCode",

"Production_Tracking"."GetTopLevelParent_WithView_1"("tbl_BuiltAssemblies"."ChildBarCode")
AS parents
FROM "Production_Tracking"."tbl_BuiltAssemblies";

These views seem to run, but never display data.

Any help would be most appreciated.

Thanks,
Karen

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Zlatko Matić

zlatko.matic1@sb.t-com.hr

almost 19 years ago

In reply to: Karen Springer (#1)

plpgsql equivalent to plperl $_SHARED and plpythonu global dictionary GD?

Does plpgsql has something equivalent to plperl $_SHARED or plpythonu global
dictionary GD?
Thanks,

Zlatko

hubert depesz lubaczewski

depesz@gmail.com

over 18 years ago

In reply to: Zlatko Matić (#3)

Re: plpgsql equivalent to plperl $_SHARED and plpythonu global dictionary GD?

On 7/9/07, Zlatko Matic <zlatko.matic1@sb.t-com.hr> wrote:

Does plpgsql has something equivalent to plperl $_SHARED or plpythonu
global
dictionary GD?

no, but you can use some table to emulate this. or a temp table.

depesz

--
http://www.depesz.com/ - nowy, lepszy depesz

Zlatko Matić

zlatko.matic1@sb.t-com.hr

over 18 years ago

In reply to: Karen Springer (#1)

Re: plpgsql equivalent to plperl $_SHARED and plpythonu global dictionary GD?

Hello.
OK. I created a new table that holds information about rows inserted/updated in a transaction.
I realized that after row-level trigger fires always before after statement-level trigger.
Therefore I can use row-level triger to populate the auxiliary table which holds information about affected rows, so that after statement-level trigger can read that information.
It works and is fast enough.
So, I emulated NEW and OLD for statement level trigger:)
Regards,

Zlatko
----- Original Message -----
From: hubert depesz lubaczewski
To: Zlatko Matic
Cc: pgsql-general@postgresql.org
Sent: Tuesday, July 10, 2007 10:17 AM
Subject: Re: [GENERAL] plpgsql equivalent to plperl $_SHARED and plpythonu global dictionary GD?

On 7/9/07, Zlatko Matic <zlatko.matic1@sb.t-com.hr> wrote:
Does plpgsql has something equivalent to plperl $_SHARED or plpythonu global
dictionary GD?

no, but you can use some table to emulate this. or a temp table.

depesz

--
http://www.depesz.com/ - nowy, lepszy depesz

Karen Springer

karen.springer@wulfsberg.com

over 18 years ago

In reply to: Pavel Stehule (#2)

Re: recursive function

Hi,

Thanks Pavel. Here's my working function. Maybe it will save someone
else some time.

CREATE OR REPLACE FUNCTION "Production_Tracking"."GetTopLevelParent"()
RETURNS SETOF record AS
$BODY$

DECLARE

initial_rec RECORD;
rec RECORD;
parentbc varchar;
toplevelparentbc varchar;

BEGIN

FOR initial_rec IN SELECT "ChildBarCode" FROM
"Production_Tracking"."tbl_BuiltAssemblies" LOOP

SELECT INTO parentbc "tbl_BuiltAssemblies"."ParentBarCode" FROM
"Production_Tracking"."tbl_BuiltAssemblies" WHERE
"tbl_BuiltAssemblies"."ChildBarCode" = initial_rec."ChildBarCode";

toplevelparentbc := parentbc;

WHILE FOUND LOOP
SELECT INTO parentbc "tbl_BuiltAssemblies"."ParentBarCode" FROM
"Production_Tracking"."tbl_BuiltAssemblies" WHERE
"tbl_BuiltAssemblies"."ChildBarCode" = parentbc;
IF NOT(parentbc IS NULL) THEN
toplevelparentbc := parentbc;
END IF;
END LOOP;

rec := (toplevelparentbc,initial_rec."ChildBarCode");

RETURN NEXT rec;

END LOOP;

RETURN;

END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;

CREATE OR REPLACE VIEW "Production_Tracking"."tvw_GetTopLevelParent" AS
SELECT "GetTopLevelParent"."TopLevelParent",
"GetTopLevelParent"."InitialBarCode"
FROM "Production_Tracking"."GetTopLevelParent"()
"GetTopLevelParent"("TopLevelParent" character varying, "InitialBarCode"
character varying);

Example if given:
ParentBarCode ChildBarCode
W1 W2
W2 W3
W3 W4
This function will return
toplevelparentbc ChildBarCode
W1 W2
W1 W3
W1 W4';

Karen

Pavel Stehule wrote:

Show quoted text

Hello

please, look on
http://people.planetpostgresql.org/merlin/index.php?/archives/2-Dealing-With-Recursive-Sets-With-PLPGSQL.html

Regards
Pavel Stehule

2007/6/13, Karen Springer <karen.springer@wulfsberg.com>:

Hi,

I am struggling to write my first recursive function and think I'm
missing something basic. I have written 2 functions that work if I pass
over one parameter, but if I try to pass over a series of parameters say
in a view for every field in the table it seems to run but never
displays data.

I have a table of built units.

tbl_BuiltAssemblies
ParentBarCode varchar(12)
ChildBarCode varchar(12)

I need to find the end ParentBarCode (Top Level) for each child. So if
I have

Parent Child
1 2
2 3
2 4
3 5

If I feed the function child 5, 4, 3, or 2, I need to get parent 1.
Since these are built units, each child can only be in one parent.

So far I've written this function which works great when passing over
one parameter.

CREATE OR REPLACE FUNCTION
"Production_Tracking"."GetTopLevelParent_WithView"(varchar)
RETURNS TEXT AS '

DECLARE
childBarCode ALIAS FOR $1;
parentBarCode TEXT;
topLevelParentBarCode TEXT;
BEGIN

SELECT INTO parentBarCode
"tbl_BuiltAssemblies"."ParentBarCode"
FROM "Production_Tracking"."tbl_BuiltAssemblies"
WHERE "tbl_BuiltAssemblies"."ChildBarCode" = childBarCode;

topLevelParentBarCode = parentBarCode;

WHILE FOUND LOOP
SELECT INTO parentBarCode
"tbl_BuiltAssemblies"."ParentBarCode"
FROM "Production_Tracking"."tbl_BuiltAssemblies"
WHERE "tbl_BuiltAssemblies"."ChildBarCode" = parentBarCode;
IF NOT(parentBarCode IS NULL) THEN
topLevelParentBarCode = parentBarCode;
END IF;
END LOOP;

RETURN (topLevelParentBarCode)::TEXT;

END;
' LANGUAGE 'plpgsql';

I have also written this too which again works great if I pass over one
parameter. (I would add a Level field to this & get the max level
eventually, but I don't want to spend more time on it until I know I'm
on the right track.)

CREATE OR REPLACE FUNCTION
"Production_Tracking"."GetTopLevelParent_WithView_1"(varchar)
RETURNS SETOF "Production_Tracking".cattree AS'

DECLARE
childbarcode ALIAS FOR $1;
parentbarcode "Production_Tracking".cattree%ROWTYPE;
toplevelparentbarcode "Production_Tracking".cattree%ROWTYPE;
BEGIN

FOR parentbarcode IN SELECT "ParentBarCode", childbarcode AS
"InitialChild"
FROM "Production_Tracking"."tbl_BuiltAssemblies" WHERE
"tbl_BuiltAssemblies"."ChildBarCode" = childbarcode LOOP

RETURN NEXT parentbarcode;

FOR toplevelparentbarcode IN SELECT "ParentBarCode",
childbarcode AS "InitialChild"
FROM
"Production_Tracking"."GetTopLevelParent_WithView_1"(parentbarcode."ParentBarCode")

LOOP

RETURN NEXT toplevelparentbarcode;

END LOOP;

END LOOP;

RETURN;

END;
' LANGUAGE 'plpgsql';

Here are examples of the views I've tried

SELECT "tbl_BuiltAssemblies"."ChildBarCode",

"Production_Tracking"."GetTopLevelParent_WithView"("tbl_BuiltAssemblies"."ChildBarCode")

AS "TopLevelParent"
FROM "Production_Tracking"."tbl_BuiltAssemblies";

and

SELECT "tbl_BuiltAssemblies"."ChildBarCode",

"Production_Tracking"."GetTopLevelParent_WithView_1"("tbl_BuiltAssemblies"."ChildBarCode")

AS parents
FROM "Production_Tracking"."tbl_BuiltAssemblies";

These views seem to run, but never display data.

Any help would be most appreciated.

Thanks,
Karen

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq