MySQL cumulative sum grouped by date

Question

I know there have been a few posts related to this, but my case is a little bit different and I wanted to get some help on this.

I need to pull some data out of the

Answer 1

New Answer

At first, I didn't understand you were trying to do a running total. Here is how that would look:

SET @runningTotal = 0;
SELECT 
    e_date,
    num_interactions,
    @runningTotal := @runningTotal + totals.num_interactions AS runningTotal
FROM
(SELECT 
    DATE(eDate) AS e_date,
    COUNT(*) AS num_interactions
FROM example AS e
GROUP BY DATE(e.Date)) totals
ORDER BY e_date;

Original Answer

You could be getting duplicates because of your join. Maybe e1 has more than one match for some rows which is inflating your count. Either that or the comparison in your join is also comparing the seconds, which is not what you expect.

Anyhow, instead of chopping the datetime field into days and months, just strip the time from it. Here is how you do that.

SELECT
   DATE(e.Date) AS e_date,
   count(e.ID) AS num_interactions
FROM example AS e
JOIN example e1 ON DATE(e1.Date) <= DATE(e.Date)
GROUP BY DATE(e.Date);

Answer 2

I figured out what I needed to do last night... but since I'm new to this I couldn't post it then... what I did that worked was this:

SELECT
   DATE(e.Date) AS e_date,
   count(e.ID) AS num_daily_interactions,
   (
      SELECT 
         COUNT(id)
      FROM example 
      WHERE DATE(Date) <= e_date
   ) as total_interactions_per_day
FROM example AS e
GROUP BY e_date;

Would that be less efficient than your query? I may just do the calculation in python after pulling out the count per day if its more efficient, because this will be on the scale of thousands to hundred of thousands of rows returned.