Dealing with overlapping conditions in CASE statement

Question

SELECT (CASE WHEN ymd BETWEEN CURRENT_DATE -4 AND CURRENT_DATE -1 THEN '3day total' 
WHEN ymd BETWEEN CURRENT_DATE -11 AND CURRENT_DATE -1 THEN '10day total' 
WHEN ymd BETWEEN CURRENT_DATE -31 AND CURRENT_DATE -1 THEN '30day total' END) AS 'Period',
SUM(cost) cost
FROM table
WHERE ymd BETWEEN CURRENT_DATE -31 AND CURRENT_DATE -1
GROUP BY 1

The result actually seems to give me Period buckets of days 1-3, days 4-10 and days 11-30. I believe this is because there are overlapping conditions and SQL stops processing the CASE statement as soon as the first condition is met.

What I want are the totals for each bucket (ie 3 day sum, 10 day sum and 30 day sum).

Is there a way to do this without adding additional fields?

PS - the syntax is a bit different then traditional sql because it's vsql (vertica).

Answer 1

Make three totals instead of one total, and use the condition to determine where to count each record instead of trying to determine a period for a single total:

select
  sum(case when ymd between CURRENT_DATE - 4 and CURRENT_DATE - 1 then cost else 0 end) as '3day total',
  sum(case when ymd BETWEEN CURRENT_DATE - 11 and CURRENT_DATE - 5 then cost else 0 end) as '10day total',
  sum(case when ymd BETWEEN CURRENT_DATE - 31 and CURRENT_DATE - 12 then cost else 0 end) as '30day total'
from
  table
and
  ymd between CURRENT_DATE -31 and CURRENT_DATE -1
group by
  1

Note: I'm not sure which date ranges you want to count where, so I made them so that they don't overlap, as that makes most sense if you have using between. If you still want them to overlap then you can just make a comparison instead of using between as any values later than CURRENT_DATE - 1 are already filtered out.

Edit:

To get the result in rows, you can make a union between selects:

select '3day total' as period, sum(cost) as cost
from table
where ymd between CURRENT_DATE - 4 and CURRENT_DATE - 1
union all
select '10day total', sum(cost)
from table
where ymd BETWEEN CURRENT_DATE - 11 and CURRENT_DATE - 5
union all
select '30day total', sum(cost)
from table
where ymd BETWEEN CURRENT_DATE - 31 and CURRENT_DATE - 12