Single SQl Query with different where conditions

Question

Experts,
I have a requirement to design a report. Here are the details
I have Report table layout
Profit center Gross sales (This Year) Gross Sales (Last Year) % change Year of Year
The Report has a selection of entering the Start Date.
I have a single table in oracle which has profit center and Gross Sales Values on daily basis.
I want to write a single sql query to calculate both Gross Sales current year and Gross Sales Last Year. I can calculate Gross Sales Current Year by putting the where condition for start date = Current Year Date which i pass through report. I want to calculate the Gross Sales Last Year in the Same query by putting the different where condition i.e start date = Last Year date based on the date input.
I dont know how to put two where conditions in single query for two different columns.
Any help will be appreciated.
Thanks in advance
Regards
Santosh

Answer 1

instead of changing your where clause couldn't you just determine the yearly totals from your table and then use the lag statement to get last years total?
something like this?
I just made up 10,000 days worth of sales and called it fake table it is supposed to represent a variant of the table you were describing as your base table.
with fake_table as
( select trunc(sysdate + level) the_day,
level daily_gross_sales
from dual
connect by level < 10001
select yr, year_gross_sale, lag(year_gross_sale) over (order by yr) prev_year_gross_sale,
(year_gross_sale - lag(year_gross_sale) over (order by yr))/year_gross_sale * 100 percent_change
from
(select distinct yr, year_gross_sale from
select the_day,
daily_gross_sales,
extract(year from the_day) yr,
extract(year from add_months(the_day,12)) next_yr,
sum(daily_gross_sales) over (partition by extract(year from the_day)) year_gross_sale
from fake_table
order by yr
)