drop function update_job (int4,text,text,int4);
CREATE FUNCTION update_job (int4,text,text,int4) RETURNS int2 AS '
DECLARE
    c_id_ins int4; j_name_ins text;  l_ins text; 
    job_id1 ALIAS FOR $4; oid1 int4; test_id int4 := 0;
    record1 RECORD; record2 RECORD; record3 RECORD; record4 RECORD; record5 RECORD;  
    return_int4 int4 := 0; job_no1 int4 := 0;
BEGIN
   j_name_ins := $2; l_ins  := $3; c_id_ins := $1;

     -- Algunos procedimientos Perl. 
     -- Limpiar el nombre de job.
   SELECT INTO record4 clean_text(j_name_ins) as text1;
   j_name_ins = record4.text1;
     -- Limpiar la localización de job. 
   SELECT INTO record5 clean_text(l_ins) as text1;
   l_ins = record5.text1;
     -- Verificar que los valores que insertamos son correctos. 
   SELECT INTO record3 job_values_verify (c_id_ins, j_name_ins, l_ins) as no;
   IF record3.no < 0 THEN return (record3.no); END IF;

     -- Mira si existe un nombre duplicado de job para ese contacto.
   FOR record1 IN SELECT job_id FROM jobs  
      where contact_id = c_id_ins and job_name = j_name_ins
        and job_id != job_id1
      LOOP
      test_id := record1.job_id;
   END LOOP;
     -- Si job_id es nulo, genial, de otro modo suspender y devolver -1;
   IF test_id > 0 THEN return (-1); END IF;

     -- Mirar si job existe, de otro modo devolver -2.
   FOR record1 IN SELECT * FROM jobs where job_id = job_id1  
      LOOP
      update jobs set contact_id = c_id_ins,  
        job_name = j_name_ins, job_location = l_ins
	where job_id = job_id1;
      GET DIAGNOSTICS return_int4 = ROW_COUNT;
      test_id := 1;
      job_no1 := record1.job_no;
   END LOOP;

     -- Si no existe, ¿qué estamos actualizando? devolver error. 
   IF test_id = 0 THEN return (-2); END IF;

     -- Todo ha terminado, devolver return_int4.
   insert into jobs_backup (contact_id, job_no, job_name, job_location, action, error_code, job_id)
        values (c_id_ins, job_no1, j_name_ins, l_ins, ''update'', return_int4, job_id1);
   return (return_int4);
END;
' LANGUAGE 'plpgsql';
select update_job (3,'Changing title and owner.','Boston, MA',1);
select * from jobs;
  -- Deberías obtener un error con eso porque estás duplicando el nombre 
  -- y el id de contact. 
select update_job (3,'Changing title and owner.','Boston, MA',1);