Update a table using summed values from another table in MySQL/mariaDB
Assumptions:


L.L_EXTENDEDPRICE should be L.L_EXTPRICE
L_DISCOUNT and L_TAX are percentages, in which case the values stored in LINEITEM need to first be divided by 100.0 before performing calculations


Some sample data:

drop table if exists LINEITEM;
drop table if exists ORDERS;

create table ORDERS
(O_ORDERKEY      int
,O_TOTALPRICE    decimal(10,2));

insert into ORDERS values
(1,0.0),
(2,0.0);

create table LINEITEM
(L_ORDERKEY      int
,L_EXTPRICE      decimal(10,2)
,L_DISCOUNT      decimal(10,2)
,L_TAX           decimal(10,2));

insert into LINEITEM values
(1,12.99,20, 8.5),
(1, 8.99,30,11),
(2,99.99,10,10),
(2,49.99, 0, 8.5),
(2, 3.99,50,14.7);


Contents of ORDERS before the update:

select * from ORDERS;

O_ORDERKEY  O_TOTALPRICE
----------  ------------
         1          0.00
         2          0.00


Proposed update statement:

update ORDERS O
set    O.O_TOTALPRICE  = (select sum(L.L_EXTPRICE * (1 - L.L_DISCOUNT/100.0) * (1 + L.L_TAX/100.0))
                         from   LINEITEM L
                         where  L.L_ORDERKEY = O.O_ORDERKEY);


Contents of ORDERS after the update:

select * from ORDERS;

O_ORDERKEY  O_TOTALPRICE
----------  ------------
         1         18.26
         2        155.52


Here's a rextester fiddle of the above.