PostGIS stored procedure return type

There are many Postgresql stored procedure returns a value, which is recorded in advance only through your own use, and slowly expand

1, type type, where the geometry can be any type of postgresql support (integer / text / character varying .....)

CREATE OR REPLACE FUNCTION test(
    tbl character varying)
  RETURNS geometry AS
$BODY$  
DECLARE   
    v_res the Geometry; - the end result 
the begin 
    return v_res;  
 End ;  
$BODY$
  LANGUAGE plpgsql VOLATILE STRICT
  COST 100;
ALTER FUNCTION test(character varying)
  OWNER TO postgres;

2, table type, a return data set, define a return needs its own field, here select query execution returns with return

CREATE OR REPLACE FUNCTION test(
    IN tbl character varying)
  RETURNS TABLE(v_gid integer, v_res geometry) AS
$BODY$  
DECLARE   
the begin  
    - execution returns a result 
    return Query
     SELECT v_uptap_gid AS res_uptap_gid, v_uptap_geom AS res_uptap_geom;
 End ;  
$BODY$
  LANGUAGE plpgsql VOLATILE STRICT
  COST 100
  ROWS 1000;
ALTER FUNCTION test(character varying)
  OWNER TO postgres;

3, setof table / view model, returned to a data set, the data returned is usually a table lookup

But it must be an existing field in the table, the new field will not do (for example, I want to identify the type 'select type, a. * From tb a' upon return)

Convenient place is not defined return force field ( 'select * from tb' may be)

CREATE OR REPLACE FUNCTION test(
    IN tbl character varying)
  RETURNS SETOF table1 AS
$BODY$  
declare  
begin 
    SELECT * from table1; 
    --或者
    return query select * from table1;
end;  
$BODY$
  LANGUAGE plpgsql VOLATILE STRICT
  COST 100
  ROWS 1000;
ALTER FUNCTION test(character varying)
  OWNER TO postgres;

3, setof record type A data set is returned, similar to the setof table

The difference is that I can return setof record all the fields, calling for people to take the field

CREATE OR REPLACE FUNCTION test(
    IN tbl character varying)
  RETURNS SETOF record AS
$BODY$  
declare  
r record;
begin 
    for r in EXECUTE 'select * from tb'  loop
       return next r;
    end loop;
    return;
end;  
$BODY$
  LANGUAGE plpgsql VOLATILE STRICT
  COST 100
  ROWS 1000;
ALTER FUNCTION test(character varying)
  OWNER TO postgres;

--调用
select * from test('tb')  as member(id int, name text);