ID | GOODS_ID | PRICE | DATE_BEGIN | DATE_END
 1    100        50     01/01/2022   null
 2    100        65     01/02/2022   30/03/2022
 3    100        75     01/05/2022   null
 4    100       100     01/07/2022   null

SELECT * FROM PRICES WHERE GOODS_ID = 100 AND DATE_END IS NULL

CREATE TABLE ITEM_PRICE_DOC (
    ID          INTEGER NOT NULL,
    ID_ITEM     INTEGER NOT NULL,
    ID_NPRICE   INTEGER NOT NULL,
    DATE_START  DATE,
    PRICE       NUMERIC(12,4),
    ID_DOC      INTEGER,
);

ALTER TABLE ITEM_PRICE_DOC ADD CONSTRAINT PK_ITEM_PRICE_DOC PRIMARY KEY (ID);

ALTER TABLE ITEM_PRICE_DOC ADD CONSTRAINT FK_ITEM_PRICE_DOC_1 FOREIGN KEY (ID_DOC) REFERENCES DOC (ID) ON DELETE CASCADE;
ALTER TABLE ITEM_PRICE_DOC ADD CONSTRAINT FK_ITEM_PRICE_DOC_2 FOREIGN KEY (ID_ITEM) REFERENCES ITEM (ID);

CREATE DESCENDING INDEX ITEM_PRICE_DOC_IDX2 ON ITEM_PRICE_DOC (ID_ITEM, ID_NPRICE, DATE_START, PRICE);

create or alter procedure GET_ITEM_PRICE (
    ID_ITEM integer,
    ID_NPRICE integer,
    DATE_NK date = null)
returns (
    PRICE numeric(12,4),
    DATE_START date,
    ID_DOC integer,
    ID integer)
as
begin
  if (id_nprice <> 0) then
  begin
    select first 1 price, date_start, id_doc, id from item_price_doc
    where id_item = :id_item and id_nprice = :id_nprice and
          date_start <= coalesce(:date_nk, max_date())
    order by date_start desc, price desc
    into price, date_start, id_doc, id;
  end

  price = coalesce(price, 0);
  suspend;
end