在单个查询中获取两个日期范围不同的记录

Question

I have sales table and have two different date ranges. ie, I have total sales between (2016-12-21 - 2016-12-30) is 100 and for period (2016-12-11 - 2016-12-20) is 85 . Now the result I want is

100 (sales of 2016-12-21 - 2016-12-30), 85 (sales of 2016-12-11 - 2016-12-20), 15 (difference of both periods) through single query.

What I am thinking is

select *, (a.sales - b.sales) as diff 
from (select id, sum(sales) as sales from salestable where date >= '2016-12-21' and date <= '2016-12-30') a 
join (select id, sum(sales) as sales from salestable where date >= '2016-12-11' and date <= '2016-12-20') b
on a.id = b.id;

Is there any other better way to do this?

Answer 1

You can use conditional aggregation:

select sum(case when date >= '2016-12-21' and date <= '2016-12-30' then sales else 0
           end) as sales_a,
       sum(case when date >= '2016-12-11' and date <= '2016-12-20' then sales else 0
           end) as sales_b,
       sum(case when date >= '2016-12-21' and date <= '2016-12-30'
                then sales else 0
                when date >= '2016-12-11' and date <= '2016-12-20'
                then -sales
                else 0
           end) as sales_diff
from salestable;

If you want the overall sum by id (as suggested by your inclusion of id ), then add id to the select and add group by id .

Answer 2

You can use case to do a conditional sum like this:

select id,
    sum_21_to_30, 
    sum_11_to_20, 
    sum_21_to_30 - sum_11_to_20 diff
from (select id,
    sum(case when date >= '2016-12-21' and date <= '2016-12-30' then sales else 0 end) sum_21_to_30,
    sum(case when date >= '2016-12-11' and date <= '2016-12-20' then sales else 0 end) sum_11_to_20
from table group by id) t;