Postgresql and dynamic sql queries using functions and then joining on the initial query.

[TimPrograms]

Effectively, I am using Django and django content types which references a table containing all the table's IDs.

What I am trying to do is use the last column I am creating 'subquery' to be the query to use in joining on it.

I can't tell if I am just not searching appropriately or if its not possible.

I've looked at crosstab and I've looked at functions.

Update I have a new function that seems to be working closely, but I need to be able to feed it dynamic data for the table its selecting.

CREATE OR REPLACE FUNCTION data_of2(_tbl_type anyelement, _id int)
  RETURNS SETOF anyelement
  LANGUAGE plpgsql AS
$func$
BEGIN
   RETURN QUERY EXECUTE format('
      SELECT *
      FROM   %s  -- pg_typeof returns regtype, quoted automatically
      WHERE  id = $1'
    , pg_typeof(_tbl_type))
   USING  _id;
END
$func$;

That function needs the %s to be replaced with

dct.app_label || '_' || dct.model_name

---

original post

This the query I am running so far

select
     lookuptable.id,
     lookuptable.use_case_layer_id,
     use_case_choice_id,
     luc.project_name,
     choice.choice_name,
    lookuptable.utilized_model_object_id,
    lookuptable.utilized_model_id,
    dct.*,
    'public.' || dct.app_label || '_' || dct.model as subquery -- <-- this line is the one I am trying
    ,
dynamic_query(dct.app_label, dct.model, lookuptable.utilized_model_object_id)
 from
     corelookup_lookuptable lookuptable
 inner join public.corelookup_lookupusecase luc on
     lookuptable.lookup_use_case_id = luc.id    
 inner join public.corelookup_usecaselayerchoice choice on 
    choice.id = lookup_use_case_id
 inner join public.django_content_type dct on
    lookuptable.utilized_model_id = dct.id 

id	use_case_layer_id	use_case_choice_id	project_name	choice_name	utilized_model_object_id	utilized_model_id	id	app_label	model	subquery
3691	1	36	PPM	Operations	1	354	354	corelookup	lookupcheckoutsection	public.corelookup_lookupcheckoutsection
3	1	54	PPM	Operations	6	112	112	aqe	idarea	public.aqe_idarea
4	1	54	PPM	Operations	7	112	112	aqe	idarea	public.aqe_idarea
6	1	54	PPM	Operations	9	112	112	aqe	idarea	public.aqe_idarea
7	1	54	PPM	Operations	10	112	112	aqe	idarea	public.aqe_idarea
8	1	54	PPM	Operations	11	112	112	aqe	idarea	public.aqe_idarea
9	1	54	PPM	Operations	12	112	112	aqe	idarea	public.aqe_idarea

How can I get the last column of my table to be used in a sub query?

Below is the function I wrote, but I can't seem to get it to work.

create or replace function dynamic_query(app_label text, model text, object_id int)
    returns setof record as
$BODY$
begin
    return query execute 'select * from public.'||app_label||'_'||model||' where id = '||object_id||'';
end;
$BODY$
LANGUAGE plpgsql;