Re: cycling through custom type fields

Hello

2011/5/19 Julius Tuskenis <julius@nsoft.lt>:
> Hello,
>
> I would like to ask if there is a possibility in postgresql (v9) to cycle
> through the fields of some custom type parameter in plpgsql function.
>
> I have a type defined:
> CREATE TYPE naims.frt_pwd_ed AS
>   (pwd_id integer,
>    pwd_sub_id integer,
>    pwd_login character varying(100));
>
> In pseudocode thats what I'd like to achieve:
>
> function Changes(prm_old_pwd  naims.frt_pwd_ed, prm_new_pwd
> naims.frt_pwd_ed)
> returns set of text
> begin
>  FOR i = 0 to naims.frt_pwd_ed.FieldCount -1 LOOP
>    IF prm_old_pwd.field(i).value <> prm_new_pwd.field(i).value THEN
>      Return Next prm_old_pwd.field(i).fieldname;
>    END IF;
>  END LOOP;
>  Return;
> end;
>
> The functrion should check each field of 2 provided parameters and return
> the fieldnames where the values are different. For this I need some tools to
> extract field value and field name. Can this be done?
>
> Thank You in advance!
>
> --

It isn't possible directly

you can

a) use a PLPerl or a PLPython
b) use some lib like pltoolbox http://www.pgsql.cz/index.php/PL_toolbox_%28en%29
c) use a EXECUTE USING trick
http://okbob.blogspot.com/2008/06/execute-using-feature-in-postgresql-84.html
d) use a hstore contrib module
http://okbob.blogspot.com/2009/10/dynamic-access-to-record-fields-in.html

Regards

Pavel Stehule


> Julius Tuskenis
> Programavimo skyriaus vadovas
> UAB nSoft
> mob. +37068233050
>
>
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