MySql Get sum by date range - mysql

Question

Here is some table for storing advertising campaign budgets history:
campaign_budgets_history
id_campaign budget date
1 10 2013-01-01
1 15 2013-01-03
1 10 2013-01-05
If there are no data for some date, it would be equal to the last set budget.
How can I count the sum of budgets by date range, for example from '2013-01-02' to '2013-01-06'. The result must be $60, because of the budget for '2013-01-02' would be equal to '2013-01-01', and budget for '2013-01-04' would be equal to '2013-01-03'.
Is there are any way to do it via SQL?

Answer 1

Here is a query for you. It uses user variables to denote the ends of the query range, but in the final version you'll likely rather use parameter placeholders instead. Note that #end is the first day after the range you query, i.e. it's the exclusive end of the range.
SET #begin = '2013-01-02';
SET #end = '2013-01-07';
SELECT
SUM(DATEDIFF(IF(CAST(c.end AS date) > CAST(#end AS date),
CAST(#end AS date),
CAST(c.end AS date)
),
IF(c.begin < CAST(#begin AS date),
CAST(#begin AS date),
c.begin
)
) * c.budget
) AS overall_budget
FROM
(SELECT a.id_campaign,
a.date begin,
MIN(IFNULL(b.date, CAST(#end AS date))) end,
a.budget
FROM campaign_budgets_history a
LEFT JOIN campaign_budgets_history b
ON a.id_campaign = b.id_campaign AND a.date < b.date
WHERE a.date < CAST(#end AS date)
GROUP BY a.id_campaign, a.date
HAVING end > CAST(#begin AS date)
) c;
Tested on SQL Fiddle. Not sure why all the casts seem necessary, perhaps there is a way to avoid some of them. But the above appears to work, and some versions with less casts did not.
The idea is that the subquery creates a table of ranges, each denoting the dates where a given budget was in effect. You might have to adjust the beginning of the first range, to match the beginning of your query range. Then you simply subtract the dates to obtain the number of days for each, and multiply that number by the daily budget.

Answer 2

This example uses a calendar (utility) table...
SELECT * FROM calendar WHERE dt BETWEEN '2012-12-27' AND '2013-01-12';
+------------+
| dt |
+------------+
| 2012-12-27 |
| 2012-12-28 |
| 2012-12-29 |
| 2012-12-30 |
| 2012-12-31 |
| 2013-01-01 |
| 2013-01-02 |
| 2013-01-03 |
| 2013-01-04 |
| 2013-01-05 |
| 2013-01-06 |
| 2013-01-07 |
| 2013-01-08 |
| 2013-01-09 |
| 2013-01-10 |
| 2013-01-11 |
| 2013-01-12 |
+------------+
SELECT SUM(budget) total
FROM campaign_budgets_history a
JOIN
( SELECT MAX(y.date) max_date
FROM calendar x
JOIN campaign_budgets_history y
ON y.date <= x.dt
WHERE x.dt BETWEEN '2013-01-02' AND '2013-01-06'
GROUP
BY x.dt
) b
ON b.max_date = a.date;