Updating open orders from a price list within a range of dates
I used you dbfiddler code in the following solution that uses CROSS APPLY

declare @price_list table(product varchar(20), price int, date_price datetime, base int, active tinyint);
insert into @price_list values
('0125',  90, '2017-01-01', 1200, 0), 
('0125', 100, '2017-01-25', 1000, 1), 
('0125', 110, '2017-02-27', 500,  1),
('1200', 140, '2017-01-01', 2000, 0), 
('1200', 150, '2017-02-01', 1500, 1), 
('1200', 160, '2017-02-27', 1000, 1);

declare @orders table(product varchar(20), order_date datetime, price int, base int);
insert into @orders values
('0125', '2017-02-19', 100, 1000), 
('0125', '2017-02-20', 100, 1000),
('0125', '2017-02-21', 100, 1000), 
('0125', '2017-02-22', 100, 1000),
('0125', '2017-02-23', 100, 1000), 
('0125', '2017-02-28', 110,  500),
('1200', '2017-02-19', 150, 1500), 
('1200', '2017-02-20', 150, 1500),
('1200', '2017-02-21', 150, 1500), 
('1200', '2017-02-22', 150, 1500),
('1200', '2017-02-23', 150, 1500), 
('1200', '2017-02-28', 160, 1000);



declare @new_date_price datetime = '2017-02-21';


-- add a new price to the list
--
insert into @price_list values ('0125', 105, @new_date_price - 1, 1300, 1);
insert into @price_list values ('1200', 155, @new_date_price - 1, 1400, 1);


-- update orders price and base, according products price list date price
--
-- I'd like to avoid use 2 (or more) subqueries
--
UPDATE o
SET o.Price = ca.price
    ,o.base = ca.base
FROM @Orders o
CROSS APPLY (
    SELECT TOP 1 pl.price AS price
        ,pl.base AS base
    FROM @Price_List pl
    WHERE pl.product = o.product
        AND pl.date_price &lt;= o.order_date
        AND active = 1
    ORDER BY pl.date_price DESC
    ) ca
WHERE o.product IN (
        '0125'
        ,'1200'
        );--&lt;&lt;&lt; select distinct product from inserted
-- final result
--
select * from @price_list order by product, date_price;
select * from @orders order by product, order_date;