How to group results by range of days?

Question

PHP

There is a query:
SELECT SUM(sum) AS sum,start_date
FROM aes_deposit WHERE user_id=1552 AND start_date BETWEEN '12/1/2015' AND '12/31/2015' GROUP BY start_date
which selects the amount of deposits and groups by date and then displays on the chart via js (date+amount).
How to make MySQL group by date range (2 days, 3 days, etc.)?

Answer 1

For starters, you have the wrong date format in your request. If VARCHAR or TEXT is used instead of the standard DATE type, then the search will not work correctly.
Well, for grouping, it is enough to create a function that will give the same values ​​for the quantities that need to be included in one group.
And, of course, indexes will not work with such a grouping.