--drop table qz_product_price_history purge;
create table qz_product_price_history (
product_id integer not null,
start_date date not null,
end_date date,
unit_cost number(10, 2) not null,
primary key (
product\_id, start\_date
)
);
alter table qz_product_price_history
add period for prices ( start_date, end_date );
Correct syntax, but in SQL Developer 19.1:

https://docs.oracle.com/database/121/ADFNS/adfns_design.htm#ADFNS967