Thread: Recursive function

Recursive function

From

Gnanavel Shanmugam

Date:

05 July 2005, 05:05:38

Hi,
I have a table with the following details.
section_type_id | section_type_name | parent_section_type_id
-----------------+-------------------+------------------------             10 | Unit              |             20 |
Block            |                     10             30 | Practice          |                     20             40 |
SubPractice      |                     30 

I've written a function as this

CREATE or replace FUNCTION get_child_section_types(int) RETURNS setof int   AS $$    declare        v_section_type_id
aliasfor $1;        v_rec record;       begin        for v_rec in select section_type_id from master_section_type where 
parent_section_type_id=v_section_type_id loop            return next v_rec.section_type_id;        end loop;
return;      end; 
$$   LANGUAGE plpgsql;

which returns output like,

select * from get_child_section_types(10);get_child_section_types
-------------------------                     20

but I need the function to return all section types under the child nodes
too.
So, how to make the function to be recursive.

with thanks & regards,
S.Gnanavel

Re: Recursive function

From

Gnanavel Shanmugam

Date:

05 July 2005, 05:33:03

solved the problem. The modified function is

CREATE or replace FUNCTION get_child_section_types(int) RETURNS setof int   AS $$    declare        v_section_type_id
aliasfor $1;        v_rec record;        v_rec1 record;       begin        for v_rec in select section_type_id from
master_section_typewhere 
parent_section_type_id=v_section_type_id loop            return next v_rec.section_type_id;            for v_rec1 in
select* from 
get_child_section_types(v_rec.section_type_id) loop            return next v_rec1.get_child_section_types;
endloop;        end loop;        return;       end; 
$$   LANGUAGE plpgsql;

with regards,
S.Gnanavel


> -----Original Message-----
> From: s.gnanavel@inbox.com
> Sent: Mon, 4 Jul 2005 21:05:25 -0800
> To: pgsql-sql@postgresql.org
> Subject: [SQL] Recursive function
>
> Hi,
>
>  I have a table with the following details.
>
>  section_type_id | section_type_name | parent_section_type_id
> -----------------+-------------------+------------------------
>               10 | Unit              |
>               20 | Block             |                     10
>               30 | Practice          |                     20
>               40 | Sub Practice      |                     30
>
> I've written a function as this
>
> CREATE or replace FUNCTION get_child_section_types(int) RETURNS setof int
>     AS $$
>         declare
>             v_section_type_id alias for $1;
>             v_rec record;
>         begin
>             for v_rec in select section_type_id from master_section_type where
> parent_section_type_id=v_section_type_id loop
>                 return next v_rec.section_type_id;
>             end loop;
>             return;
>         end;
> $$
>     LANGUAGE plpgsql;
>
> which returns output like,
>
> select * from get_child_section_types(10);
>  get_child_section_types
> -------------------------
>                       20
>
> but I need the function to return all section types under the child nodes
> too.
> So, how to make the function to be recursive.
>
> with thanks & regards,
> S.Gnanavel
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
>        choose an index scan if your joining column's datatypes do not
>        match

Re: Recursive function

From

"Nick Stone"

Date:

05 July 2005, 06:29:27

Hi,

Also you could take a look at the connectby function as this will do what
you want with ease and it can be used to sort stuff at the same time,
produce tree views of data etc.

Nick 

-----Original Message-----
From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]
On Behalf Of Gnanavel Shanmugam
Sent: 05 July 2005 06:05
To: pgsql-sql@postgresql.org
Subject: [SQL] Recursive function

Hi,
I have a table with the following details.
section_type_id | section_type_name | parent_section_type_id
-----------------+-------------------+------------------------             10 | Unit              |             20 |
Block            |                     10             30 | Practice          |                     20             40 |
SubPractice      |                     30
 

I've written a function as this

CREATE or replace FUNCTION get_child_section_types(int) RETURNS setof int   AS $$    declare        v_section_type_id
aliasfor $1;        v_rec record;       begin        for v_rec in select section_type_id from
 
master_section_type where parent_section_type_id=v_section_type_id loop            return next v_rec.section_type_id;
    end loop;        return;       end;
 
$$   LANGUAGE plpgsql;

which returns output like,

select * from get_child_section_types(10);  get_child_section_types
-------------------------                     20

but I need the function to return all section types under the child nodes
too.
So, how to make the function to be recursive.

with thanks & regards,
S.Gnanavel
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to      choose an index scan if your joining column's
datatypesdo not      match