CREATE OR REPLACE FUNCTION public.abc (
  in "cat_id" INTEGER = 0,   in "date1" DATE = NULL,   in "date2" DATE = NULL
)
RETURNS TABLE (num bigint, items_id integer, sname varchar, fprice FLOAT,
 dola FLOAT, suma_dola float, rank char(1)) AS
$body$
DECLARE
  i int;
BEGIN
select set_config('custom.prev', '0', false);

return query select 
h.num, h.items_id, h.sname, h.fprice, h.dola, h.suma_dola,
    case
        when h.suma_dola < 0.5 then 'A'
        when h.suma_dola between 0.5 and 0.85 then 'B'
    	else 'C'
    end ::char(1) rank
from 


(

select
	f.num num,
	f.items_id,
	f.sname,
	f.fprice,
	f.dola,
	f.dola+current_setting('custom.prev')::FLOAT as suma_dola,
	set_config('custom.prev', cast(f.dola+current_setting('custom.prev')::FLOAT as text), false)
from
	(
    -- id товара, название, общая выручка, Доля накопительного итога
    select
    	row_number() over() num,
        t.items_id,
        t.sname,
        t.fprice,
        t.fprice/ sum(t.fprice) over () dola
    	from
        (
        -- id товара, название, сумма, (за указанный период + категорию)
        select
            s.items_id,
            i.sname,
            sum(s.price * s.icount) fprice
            -- c.sname
        from
            sales as s,
            items as i,
            cats as c
         where i.id = s.items_id
            and i.cat_id = c.id
           /* 
           and  i.cat_id = 59
           and s.ddate BETWEEN '01.01.2016' and '01.04.2016'
           */
        group by s.items_id, i.sname
        order by 3 desc) as t
    ) as f
) as h;



END;
$body$
LANGUAGE 'plpgsql'
VOLATILE
CALLED ON NULL INPUT
SECURITY INVOKER;

select * from abc(7, '01.01.2015', '01.01.2016');