sorry , there is a little correction: the below table will have cropid instead of date.
create table amountdifference( cropid int, productid int,amtdiff float)
insert into amountdifference
select 1,100,200.00
union
select 1,101,210.00
union
select 2,100,110.00
union
select 2,101,130.00
union
select 6,100,230.00