create table stat (
  ts timestamp,
  ip inet,
  ua text,
  uri text
);

create or replace function get_stat(time_from timestamp, time_to timestamp)
returns setof refcursor
language plpgsql as $BODY$
declare
  by_day cursor is
    select ts::date as "День",count(*) as "Запросов"
    from stat
    where ts between time_from and time_to
    group by ts::date
    order by  1 ;
  by_host cursor is
    select ip as "Адрес",count(*) as "Запросов"
    from stat
    where ts between time_from and time_to
    group by ip
    order by count(*) desc;
  by_browser cursor is
    select ua as "Браузер",count(*) as "Запросов"
    from stat
    where ts between time_from and time_to
    group by ua
    order by count(*) desc;
begin
  open by_day; return next by_day;
  open by_host; return next by_host;
  open by_browser; return next by_browser;
end;
$BODY$;

#-------------------в приложении (псевдокод)-------------------------
# открываем транзакцию
connection.begin_transaction
# получаем набор имен курсоров (aka portal names)
stat = connection.execute("SELECT * FROM get_stat('2008-02-01', '2008-02-29 23:59')")
# теперь ходим по нему и извлекаем данные
while (row = stat.fetch) do
    # извлекаем данные по полученному имени курсора
    ds = connection.execute("FETCH ALL FROM " + row[ 0 ]) 
    # формируем HTML-табличку по набору данных ds
  ...
end
# закрываем транзакцию
connection.commit
# показываем результат
...