drop table brands;
create table brands
(
Year int,
Brand varchar(20),
Amount int
);
insert into brands values (2018, 'Apple', 45000);
insert into brands values (2019, 'Apple', 35000);
insert into brands values (2020, 'Apple', 75000);
insert into brands values (2018, 'Samsung', 15000);
insert into brands values (2019, 'Samsung', 20000);
insert into brands values (2020, 'Samsung', 25000);
insert into brands values (2018, 'Nokia', 21000);
insert into brands values (2019, 'Nokia', 17000);
insert into brands values (2020, 'Nokia', 14000);
select * from brands;
with cte as (
select *,lag(amount) over(partition by brand order by year) as lag_amount
from brands )
select * from cte