-- extract sales by day, store, product
select business_date, store_code, product_code,
sum(sales) as sales
into #temp1
from sales_table
where business_date >= date_trunc('month', dateadd('month', -24, sysdate))
group by business_date, store_code, product_code;


-- compare this year against last year
select ty.*, ly.sales as sales_ly
into #temp2
from #temp1 ty left join #temp1 ly
on ty.product_code = ly.product_code
and ty.store_code = ly.store_code
and trunc(dateadd(year, -1, ty.business_date)) = ly.business_date;

-- check
select to_char(business_date, 'yyyymm'), sum(sales) ty, sum(sale_ly) as ly
from #temp2
group by to_char(business_date,'yyyymm')
order by 1;