call function postgresql 9.5

I have not found help. Now I created a function in postgresql 9.5

CREATE OR REPLACE FUNCTION certificado_notas()
RETURNS TABLE(mat_anio_academico integer, udi_id integer, udi_nombre character varying, sem_codigo character, udi_letra_nomina character, mud_nota_final integer, mud_nora_recuperacion integer, mma_id integer)
AS $BODY$
BEGIN
RETURN QUERY SELECT
m.mat_anio_academico,
mu.udi_id,
u.udi_nombre,
u.sem_codigo,
u.udi_letra_nomina,
mu.mud_nota_final,
mu.mud_nota_recuperacion,
m.mma_id

FROM (SELECT
DISTINCT ON (mud.udi_id) mud.mud_id
FROM matricula_unidad_didactica AS mud
INNER JOIN matricula AS m
ON mud.mat_id=m.mat_id
INNER JOIN alumno AS a
ON m.alu_id=a.alu_id
WHERE a.alu_id = 415
ORDER BY mud.udi_id DESC, m.mat_anio_academico DESC
) AS mudi
JOIN matricula_unidad_didactica AS mu
ON mudi.mud_id=mu.mud_id
JOIN unidad_didactica AS u
ON mu.udi_id=u.udi_id
JOIN matricula AS m
ON mu.mat_id=m.mat_id
JOIN alumno AS a
ON m.alu_id=a.alu_id
WHERE a.alu_id = 415
ORDER BY u.sem_codigo ASC, u.udi_letra_nomina ASC, m.mat_anio_academico ASC;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;


attempt to call in 2 ways.

$this->db->query("SELECT certificado_notas()");

$this->db->call_function("certificado_notas");

in both no error.

as I can call a function in codeigniter postgresql

I tried with a simpler function.

Code:

DROP FUNCTION sp_1()

CREATE OR REPLACE FUNCTION sp_1()
RETURNS TABLE(codigo character varying, nombre character varying)
AS
$$
BEGIN
RETURN QUERY SELECT sem_codigo, sem_nombre FROM semestre;
END;
$$
LANGUAGE 'plpgsql' VOLATILE;

pgadmin3 use it in this way:

Code:

SELECT codigo, nombre FROM sp_1();

so also

Code:

SELECT * FROM sp_1();

and works.

codeigniter but does not work.

Code:

$this->db->query('SELECT codigo, nombre FROM sp_1()');

or

Code:

$this->db->query('SELECT * FROM sp_1()')

the error is

ERROR: SELECT * with no tables specified is not valid LINE 1: SELECT * ^

SELECT *