Use text output from a function as new query

Question

In continuing from a previous case that was assisted by @Erwin Brandstetter and @Craig Ringer, I have fixed my code to become as follows. Note, that my function myresu

Answer 1

I think I found a solution too, using a refcursor.
I would be very glad if you could go through it, check and tell me if you think it is 'Kosher'. Frankly, I am not too sure what I've came up with here, as I am not that familiar with the syntax. But I was rather able to synthesize this using different examples I found on the web. It seems to work for me. I would be very glad if you could articulate this solution for me and for other users - and tell what do you think of it.

First lets create the function that constructs the dynamic SELECT statement:

CREATE OR REPLACE FUNCTION myresult2()
  RETURNS text AS 
$func$
DECLARE
   myoneliner text;
   mytable    text := 'dkj_p_k27ac';
   myprefix   text := 'enri';
BEGIN
   SELECT INTO myoneliner  
          'SELECT '
        || string_agg(quote_ident(column_name::text), ',' ORDER BY column_name)
        || ' FROM ' || quote_ident(mytable)
   FROM   information_schema.columns
   WHERE  table_name = mytable
   AND    column_name LIKE myprefix||'%'
   AND    table_schema = 'public';  -- schema name; might be another param

   -- RAISE NOTICE 'My additional text: %', myoneliner; -- for debugging
   RETURN myoneliner;
END
$func$ LANGUAGE plpgsql;

Now, lets create a second function that can execute the string TEXT output of the first function myresult2():

CREATE OR REPLACE FUNCTION show_mytable(ref refcursor)
  RETURNS refcursor AS
$func$
DECLARE
   mydynamicstatment text := myresult2();
BEGIN       
   OPEN ref FOR EXECUTE mydynamicstatment;
   RETURN ref;  -- return cursor to the caller
END;
$func$ LANGUAGE plpgsql;

Call:

BEGIN;
SELECT show_mytable('roy');
FETCH ALL IN "roy";